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Difficulty: MediumSubject-Verb Agreement

In materials science, the degradation rate of biodegradable polymers, which varies depending on exposure to environmental factors such as humidity and temperature, _______ the structural lifespan of medical implants. Because these temporary devices must support healing tissues before safely dissolving in the body, researchers must carefully control the rate at which the material breaks down. Which choice completes the text so that it conforms to the conventions of Standard English?

  1. A
    determine
  2. B
    determining
  3. determinesAnswer
  4. D
    have determined

Answer

determines
The correct answer is the singular verb 'determines' because it matches the singular subject of the sentence, 'degradation rate'. The intervening modifiers, such as 'of biodegradable polymers' and 'which varies depending on exposure to environmental factors', contain plural nouns, but they do not alter the singular nature of the true subject.

Step-by-Step Solution

1
Identify the main subject of the sentence containing the blank.
The subject is 'degradation rate', which is singular.
Verbs must agree in number with their grammatical subjects rather than modifying elements.
2
Identify and disregard any intervening phrases or clauses between the subject and the verb.
The prepositional phrase 'of biodegradable polymers' and the relative clause 'which varies...' contain plural nouns like 'polymers' and 'factors', but these are descriptive modifiers.
Recognizing that modifiers do not change the number of the subject helps prevent agreement errors.
3
Select the finite verb form that agrees with the singular subject.
The singular verb 'determines' is the only form that maintains subject-verb agreement.
A singular subject requires a singular verb to be grammatically correct.

Key Concept

Subject-Verb Agreement with Intervening Phrases
Estimated Time:1m 0s
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Topics

Subject-Verb Agreement

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