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Question 441Question →

The sentence below describes a historical discovery. Which form of the present-tense verb 'to illustrate' correctly completes the sentence to maintain proper subject-verb agreement?

Fill in the blanks below

The collection of vintage maps in the archives the evolution of cartography over the centuries.
Show answer & explanation

Answer

illustrates
The correct verb form is 'illustrates' because the subject of the sentence is the singular noun 'collection'. Modifying prepositional phrases like 'of vintage maps' and 'in the archives' do not change the number of the subject. A singular subject requires the singular verb form 'illustrates'.

Step-by-Step Solution

1
Identify the true grammatical subject of the sentence.
The subject of the sentence is the singular noun 'collection'.
The plural nouns 'maps' and 'archives' are the objects of the prepositional phrases 'of vintage maps' and 'in the archives' respectively, meaning they do not affect the number of the verb.
2
Determine the correct present-tense form of the verb 'to illustrate' that agrees with the singular subject.
The correct verb form is 'illustrates'.
A singular subject ('collection') requires a singular verb form ('illustrates') in the present tense.

Key Concept

Subject-verb agreement with intervening prepositional phrases
Question 442Question →

To prepare for the upcoming debate, the team captain assigned my partner and I the task of researching renewable energy policies.

Which of the following choices is the correct replacement for the underlined portion?

Show answer & explanation

Answer: partner and me

Answer

partner and me
The pronoun is part of the compound direct object of the verb 'assigned.' Removing the compound element ('my partner and') leaves 'assigned me,' which demonstrates that the objective case pronoun 'me' is required. The option containing 'partner and me' is correct.

Step-by-Step Solution

1
Identify the grammatical role of the underlined pronoun in the sentence.
The pronoun is part of a compound element ('my partner and I') that receives the action of the verb 'assigned' (assigned whom?). This means it functions as an object.
Determining whether the pronoun is a subject or an object dictates whether subjective or objective case is needed.
2
Test the pronoun case by simplifying the compound construction to just the pronoun.
The sentence becomes 'assigned me the task...' rather than 'assigned I the task...'.
Removing the other part of the compound construction makes it easier to hear which pronoun case is correct.
3
Select the option that uses the objective case pronoun 'me'.
The correct option is the one stating 'partner and me'.
'Me' is the correct objective case pronoun to serve as the object of the verb.

Key Concept

Pronoun case in compound objects
Question 443Question →

The wing structures of dragonflies, which allow them to hover and fly backward with incredible agility, are far more complex than a housefly.

Which of the following options best replaces the underlined portion to make the sentence grammatically correct and logical?

Show answer & explanation

Answer: those of a housefly

Answer

The correct option is 'those of a housefly', which correctly resolves the illogical comparison by comparing the plural noun 'wing structures' to the plural pronoun 'those' representing the wing structures of the other insect.
The correct answer correctly uses the plural pronoun 'those' to refer to the plural noun 'wing structures,' ensuring a logical and grammatically parallel comparison between the dragonfly's wing structures and the housefly's wing structures.

Step-by-Step Solution

1
Identify the two elements being compared in the sentence.
The sentence attempts to compare 'The wing structures of dragonflies' with 'a housefly'.
Comparison rules require that the compared items be equivalent in type and logically comparable.
2
Determine if the compared elements are grammatically parallel.
Comparing 'wing structures' (parts of an insect) directly to 'a housefly' (an entire insect) is grammatically incorrect and illogical.
To make the comparison logical, 'wing structures' must be compared to other 'wing structures' using a plural demonstrative pronoun like 'those'.
3
Evaluate the choices to find the one that establishes a logical, parallel comparison without introducing new grammatical errors.
The phrase 'those of a housefly' uses 'those' to refer to the wing structures, making the comparison logical and parallel, while avoiding the comma splice and parallelism errors found in the other choices.
This maintains complete grammatical correctness and clear sentence structure.

Key Concept

Illogical and Incomplete Comparisons
Estimated Time:1m 0s
Question 444Question →

The passage below contains a blank where a verb should be. Read the passage and write the correct present-tense form of the verb 'to lie' that completes the sentence with proper subject-verb agreement.

Fill in the blanks below

In the heart of the ancient ruins, hidden beneath layers of volcanic ash and dense foliage, a collection of ceramic jars containing ancient scrolls.
Show answer & explanation

Answer

lies
The correct answer is 'lies'. The sentence is written in an inverted structure where the subject follows the verb. The grammatical subject is the singular noun 'collection'. Thus, the singular present-tense verb 'lies' is required to ensure correct subject-verb agreement.

Step-by-Step Solution

1
Identify the grammatical subject of the sentence.
The subject is the noun phrase 'a collection of ceramic jars containing ancient scrolls'.
This sentence uses an inverted structure where the verb precedes the subject. The introductory prepositional and participle phrases modify the setting, but the noun performing the action of 'lying' is 'collection'.
2
Determine the number of the subject's head noun.
The head noun 'collection' is singular.
Although the subject contains plural prepositional objects like 'jars' and 'scrolls', the head noun of the subject phrase is 'collection', which is singular.
3
Match the verb to the singular subject in the present tense.
The correct singular present-tense form of the verb 'to lie' is 'lies'.
A singular subject requires a singular verb to maintain proper subject-verb agreement.

Key Concept

Subject-Verb Agreement in Inverted Sentences
Question 445Question →

Neither the chief executive officer nor the board members would discuss its views on the upcoming merger during the press conference.

Which choice best replaces the underlined portion to ensure correct pronoun-antecedent agreement?

Show answer & explanation

Answer: their

Answer

their
The correct pronoun is 'their' because it is plural and possessive, which properly agrees with the plural antecedent 'board members'—the noun closer to the pronoun in the compound subject joined by 'nor'.

Step-by-Step Solution

1
Identify the antecedent of the underlined pronoun.
The pronoun refers to the compound subject joined by 'nor': 'Neither the chief executive officer nor the board members'.
Determining the noun or nouns being replaced is the first step in establishing agreement.
2
Apply the proximity rule for compound subjects joined by 'or' or 'nor'.
The pronoun must agree in number with the closer antecedent, which is 'board members' (plural).
Standard grammar rules dictate that when parts of a compound subject are joined by 'or' or 'nor', the pronoun agrees with the nearest noun.
3
Select the possessive pronoun that matches the required number.
The plural possessive pronoun is 'their'.
A plural possessive pronoun is required to show possession for the plural noun 'board members'.

Key Concept

Pronoun-Antecedent Agreement with Compound Subjects
Estimated Time:1m 0s
Question 446Question →

During the late nineteenth century, botanist George Washington Carver worked closely with local farmers to implement new crop rotation methods. He explained the benefits of sweet potatoes to the farmers, noting that they could revitalize nitrogen-depleted soil.

Which choice best resolves the pronoun ambiguity and ensures the sentence is grammatically correct?

Show answer & explanation

Answer: these crops

Answer

these crops
The correct option replaces the ambiguous pronoun with the specific noun phrase 'these crops'. In the original sentence, the pronoun 'they' is ambiguous because it has two potential plural antecedents: 'sweet potatoes' and 'farmers'. Specifying 'these crops' removes all ambiguity and maintains a clear, concise, and grammatically correct sentence structure.

Step-by-Step Solution

1
Identify the underlined pronoun and its potential antecedents in the sentence.
The pronoun is 'they', and the preceding plural nouns are 'sweet potatoes' and 'farmers'.
To determine if the pronoun has a clear and unambiguous referent.
2
Evaluate the clarity of the pronoun reference in the context of the sentence.
The pronoun 'they' is ambiguous because it could grammatically refer to either the sweet potatoes or the farmers, even though the context implies sweet potatoes.
ACT conventions require pronouns to have a single, clear, and unambiguous antecedent.
3
Compare the options to find the one that removes the ambiguity while remaining concise and grammatically correct.
Replacing 'they' with 'these crops' provides a specific noun phrase that clearly identifies the sweet potatoes as the subject performing the action.
Using a specific noun phrase resolves the pronoun reference issue without introducing wordiness or grammatical errors.

Key Concept

Pronoun Clarity and Reference
Question 447Question →

Mangrove forests thrive in coastal saline environments, where most trees would quickly wither and die. Because these unique plants have evolved specialized root systems, which filter out up to ninety percent of the salt in seawater. This filtration process allows them to survive in waterlogged, high-salt soils that would be toxic to other flora.

Which of the following choices best replaces the underlined portion of the passage?

Show answer & explanation

Answer: These unique plants have evolved specialized root systems that filter out

Answer

These unique plants have evolved specialized root systems that filter out
The correct option removes the subordinating conjunction 'Because' and replaces the relative clause structure, creating a grammatically complete independent clause with a subject ('plants') and a predicate ('have evolved'). This successfully resolves the sentence fragment.

Step-by-Step Solution

1
Analyze the underlined portion to identify if it is a complete sentence.
The original text starts with 'Because' and contains a relative clause beginning with 'which,' which makes the entire statement a dependent clause lacking a main independent clause. This is a sentence fragment error.
Recognizing a sentence fragment is the first step in fixing grammatical structure errors on the ACT English section.
2
Evaluate the choices to see which one creates a complete, grammatically correct independent sentence.
Removing 'Because' and replacing 'which' with 'that' forms a complete sentence with a clear subject ('These unique plants') and a main verb ('have evolved').
A complete sentence requires at least one independent clause with a subject and a verb.
3
Verify that other options do not introduce new grammatical errors such as comma splices or punctuation fragments.
The option containing a semicolon creates a punctuation fragment since 'which filter out...' is dependent. The option using 'they' creates a comma splice by linking two independent clauses with only a comma.
Ensures that the selected answer is both grammatically sound and fits the punctuation rules of the test.

Key Concept

Identifying and correcting sentence fragments by ensuring the sentence contains an independent clause with a subject and a verb.
Question 448Question →

Read the passage below. To maintain consistency in verb tense and sentence structure, fill in the blank with the correct form of the verb 'inspect'.

Fill in the blanks below

In 1964, radio astronomers Arno Penzias and Robert Wilson set out to map signals from the Milky Way. Using a horn reflector antenna, they detected an unexplained, persistent buzz that they could not eliminate. To determine the source, the researchers first cleaned the antenna of nesting pigeons, and then they the system's electrical connections to rule out mechanical interference.
Show answer & explanation

Answer

inspected
The correct verb form is 'inspected' because the passage is written in the simple past tense, describing historical events from 1964. The final sentence coordinates two actions in a sequence: 'first cleaned... and then they [blank]'. To maintain parallel structure and avoid an illogical shift in verb tense, the second action must also be expressed in the simple past tense.

Step-by-Step Solution

1
Analyze the verbs in the surrounding context to determine the timeframe and mood of the passage.
The passage uses past-tense verbs ('set out', 'detected', 'could', 'cleaned') to describe historical events that occurred in 1964.
Establishing a consistent timeframe is necessary to avoid incorrect shifts in verb tense.
2
Identify the structure of the target sentence containing the blank.
The sentence uses a coordinate structure with a correlative time-sequence: 'first cleaned... and then they [blank]'.
Parallel structure requires that verbs in a coordinated sequence of actions share the same grammatical form and tense.
3
Determine the correct form of the verb 'inspect' to maintain parallel past-tense construction.
The past-tense form of 'inspect' is 'inspected'.
Using 'inspected' maintains grammatical consistency with the past-tense verb 'cleaned' and prevents an illogical shift in construction.

Key Concept

Shifts in construction occur when a writer unnecessarily changes grammatical patterns, verb tenses, or voices within a sentence or passage. Maintaining parallel structure and consistent verb tense is essential for clear writing.
Estimated Time:1m 30s
Question 449Question →

To avoid a dangling modifier, the introductory phrase must logically modify the subject of the main clause. Complete the sentence by typing the grammatically correct clause in the blank. Choose from these exact phrases (do not include ending punctuation): 'the botanists successfully germinated the ancient seeds' or 'the ancient seeds were successfully germinated by the botanists'.

Fill in the blanks below

Having survived for centuries in the arid soils of the Atacama Desert, .
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Answer

the ancient seeds were successfully germinated by the botanists
The introductory phrase 'Having survived for centuries in the arid soils of the Atacama Desert' describes the seeds. Therefore, the noun immediately following the comma must be 'the ancient seeds' to serve as the logical subject. This makes 'the ancient seeds were successfully germinated by the botanists' the correct choice.

Step-by-Step Solution

1
Identify the introductory modifying phrase and determine what it logically describes.
The phrase 'Having survived for centuries in the arid soils of the Atacama Desert' describes something that survived for centuries in dry desert soil.
Understanding the logical actor/subject of the modifier is necessary to determine which noun must immediately follow the comma.
2
Evaluate the choices to see which noun functions as the subject immediately following the comma.
In one option, the subject is 'the botanists'; in the other, the subject is 'the ancient seeds'.
The subject of the main clause must be the noun that is modified by the introductory phrase.
3
Determine which subject makes logical sense.
Botanists do not survive for centuries in desert soil, but ancient seeds do. Therefore, 'the ancient seeds' must be the subject.
Placing 'the botanists' as the subject creates a dangling modifier, whereas placing 'the ancient seeds' as the subject creates a logical, grammatically correct sentence.

Key Concept

Introductory modifying phrases must be immediately followed by the noun they logically describe to avoid creating a dangling modifier.
Estimated Time:1m 30s
Question 450Question →

A geneticist outlines the protocol for analyzing a prehistoric specimen. Arrange the following steps of the laboratory procedure in the correct chronological order, ensuring the sequence maintains parallel structure throughout the list.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence of steps in the laboratory procedure is first extracting the DNA, then amplifying the fragments, and finally sequencing the genetic data.
The correct order follows the chronological progression of a scientific workflow: first, isolating the DNA ('to extract'); second, multiplying the sample ('to amplify'); and third, analyzing the genetic sequence ('to sequence'). Each action is phrased using an infinitive, satisfying the requirements of parallel structure.

Step-by-Step Solution

1
Determine the chronological sequence of the experiment.
DNA extraction must occur before amplification, and amplification must occur before sequencing.
You cannot replicate or sequence genetic material that has not yet been isolated.
2
Check the grammatical parallel structure of the items.
Each phase starts with an infinitive: 'to extract', 'to amplify', and 'to sequence'.
Maintaining the same grammatical form across all items in a list or sequence is required for parallel structure.
3
Combine the ordered steps into a final parallel sequence.
The final order is extraction, followed by amplification, and ending with sequencing.
This configuration satisfies both chronological logic and grammatical parallelism.

Key Concept

Parallel structure requires that all items in a list or sequential process use the same grammatical form (such as infinitives, gerunds, or clauses) to maintain clarity and rhythm.
Estimated Time:1m 15s
Question 451Question →

The passage below is from an essay about cognitive development.

Although Chomsky’s theory of universal grammar suggests that the capacity for language is hardwired into the human brain, a concept that dominated twentieth-century linguistics, many contemporary researchers argue instead that language is acquired through general cognitive processes, consequently, they focus on statistical learning in infancy. By analyzing the patterns and frequencies of sounds in their environment, babies can identify word boundaries before they understand their meanings. This data-driven approach suggests that language acquisition is not unique to humans, but rather is an extension of our species' general pattern-recognition abilities.

Which of the following is the most effective and grammatically correct replacement for the underlined portion?

Show answer & explanation

Answer: processes; consequently, they focus

Answer

The option stating 'processes; consequently, they focus' is the correct answer because it uses a semicolon to connect the two independent clauses and correctly punctuates the transition word.
The correct option correctly uses a semicolon to separate two independent clauses: the first ending with 'processes' and the second beginning with 'they focus.' The conjunctive adverb 'consequently' is properly followed by a comma, establishing a logical cause-and-effect relationship without creating a comma splice.

Step-by-Step Solution

1
Analyze the grammatical structure of the clauses before and after the underlined portion.
The clause before the underlined portion is independent, and the clause after ('they focus on statistical learning in infancy') is also independent.
Identifying clause types determines what punctuation and conjunctions are required to connect them.
2
Evaluate the transition word 'consequently' to see if it acts as a coordinating conjunction.
The word 'consequently' is a conjunctive adverb, not a coordinating conjunction.
Conjunctive adverbs cannot join two independent clauses with only a comma, as this creates a comma splice.
3
Examine the alternative options to find one that separates the clauses correctly without creating fragments or punctuation errors.
Using a semicolon before 'consequently' and a comma after it correctly links the clauses. The other choices either create a sentence fragment by introducing a dependent clause or incorrectly place a comma before a restrictive 'that' clause.
A semicolon is standard punctuation for separating independent clauses, while restrictive relative clauses should not be separated from their noun by a comma.

Key Concept

Run-on Sentences and Comma Splices
Estimated Time:1m 0s
Question 452Question →

When working in the rare books archive, the head archivist reminded the head translator and I that if one wishes to handle the parchment safely, you must wear cotton gloves.

Which choice completes the sentence with the most appropriate pronoun case and person?

Show answer & explanation

Answer: me that if one wishes to handle the parchment safely, one must

Answer

me that if one wishes to handle the parchment safely, one must
The correct option correctly uses the objective case pronoun 'me' as the direct object of the verb 'reminded'. It also maintains grammatical agreement by keeping the pronoun person consistent in the third person throughout the clause, using 'one' to match 'one wishes'.

Step-by-Step Solution

1
Determine the correct case for the pronoun in the compound object.
The pronoun follows the transitive verb 'reminded' and functions as a direct object, meaning the objective case 'me' is required instead of the subjective case 'I'.
Pronouns in a compound object must use the objective case.
2
Check for pronoun person consistency in the conditional clause.
The clause begins with the third-person singular pronoun 'one' ('if one wishes...'), so shifting to the second-person pronoun 'you' ('you must') creates an inconsistent perspective. The third-person 'one must' should be used to maintain consistency.
Pronoun person must remain consistent within a sentence.

Key Concept

Pronoun Case and Person Consistency
Estimated Time:1m 15s
Question 453Question →

In the early 1950s, physical oceanographer Marie Tharp compiled bathymetric profiles collected by her colleague Bruce Heezen. While Heezen gathered sonar data aboard research vessels, Tharp painstakingly plotted these depths by hand to map the ocean floor. <u>He</u> initially dismissed her discovery of the Mid-Atlantic Ridge rift valley as 'girl talk,' attributing the feature to a temporary measurement error.

Which choice best resolves the pronoun ambiguity and ensures the sentence is grammatically correct?

Show answer & explanation

Answer: Heezen

Answer

The option that replaces the underlined pronoun with the specific noun 'Heezen' is correct because it resolves the ambiguous pronoun reference by explicitly naming the individual who dismissed the discovery, while maintaining conciseness.
The correct option replaces the ambiguous pronoun with the proper noun 'Heezen.' This resolves the ambiguity of 'He' by explicitly identifying who dismissed the discovery, maintaining a clear and direct style.

Step-by-Step Solution

1
Identify the antecedent of the underlined pronoun 'He'.
The pronoun 'He' could refer to Bruce Heezen, but because of the intervening descriptions of Tharp's work and the lack of immediate proximity, the pronoun's reference is ambiguous.
Pronouns must refer clearly and directly to a single, unambiguous antecedent.
2
Evaluate the choices to find the one that clarifies the subject without violating other grammatical rules.
Replacing 'He' with the specific proper noun 'Heezen' removes all ambiguity. Using 'They' creates a pronoun-antecedent agreement error. Using 'It was Heezen who' is grammatically correct but overly wordy.
The correct choice must be grammatically correct, precise, and as concise as possible.

Key Concept

Pronoun Clarity and Reference
Question 454Question →

Read the passage below. To maintain a consistent present-tense construction throughout the passage, fill in the blank with the correct form of the verb 'make'.

Fill in the blanks below

When amateur astronomers scan the night sky through a telescope, they look for familiar constellations and planets. If they see a shooting star, they often a wish before it disappears from sight.
Show answer & explanation

Answer

make
The correct answer is 'make' because the passage begins in the present tense with the verbs 'scan', 'look', and 'see'. To maintain a consistent present-tense construction and avoid an unnecessary shift in construction, the verb in the blank must also be in the present tense ('make') to agree with the plural subject 'they'.

Step-by-Step Solution

1
Identify the tense of the verbs established in the surrounding context of the passage.
The verbs 'scan', 'look', 'see', and 'disappears' are all in the present tense.
Establishing the timeframe of the passage is necessary to maintain construction consistency.
2
Determine the subject of the clause containing the blank to ensure proper subject-verb agreement.
The subject is the plural pronoun 'they'.
The verb must agree with both the plural subject and the established present tense.
3
Select the correct form of the verb 'make' that satisfies both present tense and plural agreement.
The base form 'make' is present tense and plural, which fits the construction.
Forms like 'made' or 'will make' introduce unnecessary shifts in tense.

Key Concept

Maintaining consistent verb tense within a passage to avoid illogical shifts in construction.
Question 455Question →

During the afternoon excursion, the tour guide led the group of visitors through the ancient temple ruins. He pointed to the stone statues positioned near the towering columns. They had been carved from imported marble centuries ago.

Which choice best maintains clarity and grammatical correctness in the underlined portion of the passage?

Show answer & explanation

Answer: the statues

Answer

Replacing the underlined pronoun with the specific noun phrase 'the statues' clarifies the sentence by identifying exactly what was carved from marble.
The correct answer replaces the ambiguous pronoun with the explicit noun phrase 'the statues'. This makes it clear that the statues—and not the columns—were carved from imported marble, resolving any potential confusion.

Step-by-Step Solution

1
Identify the underlined pronoun and locate its potential antecedents in the preceding context.
The underlined pronoun is 'They', and the preceding sentence contains two plural nouns: 'stone statues' and 'towering columns'.
To evaluate pronoun clarity, you must check if the pronoun has a single, clear, and grammatically matching noun antecedent.
2
Evaluate the answer choices to see which option replaces the ambiguous pronoun with a clear and precise term.
Replacing 'They' with the specific noun phrase 'the statues' resolves the ambiguity. The options 'NO CHANGE', 'it', and 'this' either preserve the ambiguity or introduce a new reference error.
If a pronoun can refer to more than one noun, it must be replaced by the specific noun it represents to maintain sentence clarity.

Key Concept

Pronoun Clarity and Reference
Question 456Question →

The navigation systems of migratory monarch butterflies, which rely on a solar compass and magnetic cues, are significantly more complex than a typical garden insect.

Which of the following options best replaces the underlined portion to ensure the sentence is grammatically correct and logically clear?

Show answer & explanation

Answer: those of a typical garden insect

Answer

those of a typical garden insect
The correct answer correctly uses the pronoun 'those' to represent 'navigation systems', ensuring that the plural systems of migratory monarch butterflies are logically compared to the plural systems of a typical garden insect.

Step-by-Step Solution

1
Identify the two elements being compared in the sentence.
The sentence attempts to compare 'The navigation systems of migratory monarch butterflies' to another noun phrase.
To ensure grammatical correctness, the items being compared must be of the same type (noun-to-noun or system-to-system).
2
Evaluate the underlined portion to check for comparison errors.
The underlined phrase 'a typical garden insect' compares systems to an insect, which is illogical.
An insect's navigation systems should be compared to another insect's navigation systems, not to the insect itself.
3
Select the option that corrects the comparison error without introducing new punctuation or structural errors.
Replacing the underlined portion with 'those of a typical garden insect' makes the comparison logical, where 'those' acts as a pronoun for the plural noun 'navigation systems'.
This establishes a clear, parallel, and grammatically correct comparison.

Key Concept

Illogical and Incomplete Comparisons
Estimated Time:1m 0s
Question 457Question →

Read the following sentence from a passage about mountaineering and answer the question:

'The mountaineering team completed its unusual rapid descent before the blizzard struck, securing their safety at the base camp.'

Which choice best corrects the underlined portion of the sentence?

Show answer & explanation

Answer: its unusually rapid

Answer

its unusually rapid
The correct option correctly uses the possessive pronoun 'its' to refer to the team, and the adverb 'unusually' to modify the adjective 'rapid' which describes the noun 'descent'.

Step-by-Step Solution

1
Identify the grammatical roles of the words in the underlined phrase.
In the phrase, 'descent' is a noun, 'rapid' is an adjective modifying 'descent', and the first modifier describes the degree of rapidity.
Understanding the parts of speech helps determine whether an adjective or adverb form is required.
2
Determine the correct form of the modifier modifying 'rapid'.
Since 'rapid' is an adjective, it must be modified by the adverb 'unusually' rather than the adjective 'unusual'.
Adverbs, not adjectives, are used to modify adjectives.
3
Evaluate the choices for pronoun correctness and conciseness.
The possessive pronoun 'its' is required to show possession of the descent by the team, and adding 'and quick' creates redundant phrasing.
Using 'it's' introduces a contraction error, and adding synonym modifiers violates the rule of conciseness.

Key Concept

Adjective and Adverb Usage
Estimated Time:1m 0s
Question 458Question →

During the artisan baking process, food scientists studying sourdough fermentation have identified a complex community of wild yeasts and lactobacilli. The metabolic interaction between these microorganisms, which occurs over several hours, produces lactic acid, this acid lowers the pH of the dough. Consequently, this chemical shift inhibits the growth of harmful bacteria, thereby extending the bread's shelf life.

Which of the following choices represents the most grammatically correct revision of the underlined portion of the passage?

Show answer & explanation

Answer: produces lactic acid, which lowers the pH of the dough

Answer

produces lactic acid, which lowers the pH of the dough
The correct option correctly uses a comma followed by the relative pronoun 'which' to subordinate the second clause. This resolves the comma splice by turning the second clause into a dependent relative clause that modifies 'lactic acid', resulting in a grammatically correct complex sentence.

Step-by-Step Solution

1
Analyze the original sentence structure to identify the grammatical error.
The original sentence contains two independent clauses ('The metabolic interaction... produces lactic acid' and 'this acid lowers the pH...') joined only by a comma, which is a comma splice error.
Identifying the clause boundaries helps determine what punctuation or conjunction is necessary to connect them legally.
2
Evaluate the choices to find a correction that does not introduce new errors.
Using a relative pronoun like 'which' after a comma subordinates the second clause, converting it into a dependent clause that modifies 'lactic acid'. Semicolons and periods cannot be followed by dependent clauses starting with relative pronouns unless they function as complete thoughts, which is not the case here.
This step ensures that the transition between clauses is both logically sound and grammatically correct under standard English rules.

Key Concept

Identifying and correcting comma splices and run-on sentences through proper punctuation and subordination.
Estimated Time:1m 0s
Question 459Question →

Read the passage below and select the best answer for the underlined portion.

Although the runner started the race strong, she finished more slower than her training partner.

Which choice is the correct form of the underlined phrase in the sentence above?

Show answer & explanation

Answer: more slowly

Answer

more slowly
The correct answer is 'more slowly' because the action verb 'finished' requires an adverb modifier, and comparing two runners requires a comparative form.

Step-by-Step Solution

1
Determine the part of speech required to modify the action verb 'finished'. Since it is an action verb, it must be modified by an adverb rather than an adjective.
An adverb form is required.
Adverbs modify verbs, whereas adjectives modify nouns.
2
Determine the comparative context. The sentence compares two entities (the runner and her training partner) using 'than', which requires a comparative form.
A comparative adverb is required.
Comparative forms are used to compare two things, while superlative forms are used for three or more.
3
Select the correct comparative adverb form. The adverb 'slowly' forms its comparative using 'more' ('more slowly').
The correct form is 'more slowly'.
Combining 'more' and '-er' creates an ungrammatical double comparative.

Key Concept

Selecting between adjective and adverb forms and using correct comparative modifiers to construct logical comparisons.
Question 460Question →

Walking through the park, the leash slipped out of my hand as my dog chased after a squirrel.

Which of the following versions of the underlined portion is correct?

Show answer & explanation

Answer: I dropped the leash

Answer

I dropped the leash
The correct option resolves the dangling modifier by placing the logical subject, the person doing the walking, immediately after the comma. It also maintains grammatical correctness and tense consistency.

Step-by-Step Solution

1
Identify the introductory modifying phrase and determine what it describes.
The phrase 'Walking through the park' describes an action that must be performed by a person.
Introductory participial phrases must logically modify the subject of the main clause that immediately follows the comma.
2
Check the options to find the one that puts the correct logical subject immediately after the comma and maintains correct tense.
The option 'I dropped the leash' provides the correct subject 'I' and uses the past tense verb 'dropped' to match 'chased'.
This resolves the dangling modifier while keeping the sentence grammatically correct and complete.

Key Concept

Introductory Dangling Modifiers
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