Question

Difficulty: MediumSubject-Verb Agreement

The passage below describes subterranean fungal networks in forests. Read the passage and identify the correct present-tense forms of the verbs 'to be' (for the first blank) and 'to depend' (for the second blank) that maintain proper subject-verb agreement. What are the correct verb forms to fill in the blanks?

Answer:Beneath the forest floor, a complex network of fungal threads known as mycelium connects the roots of various plants. This subterranean web of connections, which facilitates the sharing of nutrients and chemical warning signals among different species, 【is】 essential to the survival of the forest. Indeed, the vitality of the older canopy trees, as well as that of the younger saplings, 【depends】 heavily on this underground exchange.

Answer

The correct verbs are 'is' for the first blank and 'depends' for the second blank.
The correct verbs are 'is' and 'depends' because the subject of the first blank is the singular noun 'web' and the subject of the second blank is the singular noun 'vitality'. In both cases, plural nouns inside intervening phrases ('connections', 'species', 'trees', 'saplings') do not alter the grammatical number of the main subject.

Step-by-Step Solution

1
Identify the subject of the first verb.
The subject is 'web', which is singular.
The singular noun 'web' is followed by the prepositional phrase 'of connections' and a relative clause 'which facilitates the sharing... among different species'. These intervening structures do not change the grammatical number of the subject, which remains singular.
2
Determine the correct form of the verb 'to be' for the first blank.
The correct form is 'is'.
Since the subject 'web' is singular and the context is in the present tense, the third-person singular present form 'is' must be used.
3
Identify the subject of the second verb.
The subject is 'vitality', which is singular.
In the phrase 'the vitality of the older canopy trees, as well as that of the younger saplings', the core subject is 'vitality'. The prepositional phrase 'of the older canopy trees' and the additive phrase 'as well as that of the younger saplings' are parenthetical modifiers and do not affect the singular nature of the main subject.
4
Determine the correct form of the verb 'to depend' for the second blank.
The correct form is 'depends'.
Since the subject 'vitality' is singular and the sentence is written in the present tense, the singular present-tense verb 'depends' is required.

Key Concept

Subject-Verb Agreement
Estimated Time:1m 30s
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