10

Set 8: Form, Structure & Sense

Explanation

Answer: D

PASSAGE

Marine biologists have observed that coral reefs, once thought to be _______ are actually dynamic ecosystems capable of significant adaptation.

Which choice completes the text so that it conforms to the conventions of Standard English?

A. static:
B. static;
C. static
D. static,✓ Correct

Detailed Answer Explanation

This question tests your understanding of sentence function and text organization. The phrase 'once thought to be static' is a parenthetical interruption. It needs a closing comma before 'are actually' to properly resume the main clause. Each sentence in a well-constructed text serves a specific purpose. Consider what role this sentence plays in the argument: does it introduce, support, contrast, or conclude an idea? Understanding why an author includes specific sentences helps you grasp the overall argument. Each sentence should serve a clear purpose: introducing ideas, providing evidence, acknowledging counterarguments, or drawing conclusions. Identify the role to understand the structure.

Key Evidence:

• "coral reefs, once thought to be"

• "are actually dynamic ecosystems"

Why others are wrong: B (A semicolon is too strong for closing a parenthetical phrase.), A (A colon doesn't fit here; this is resuming the main clause.), C (Missing punctuation fails to close the parenthetical phrase.).

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