4

Set 1: Form, Structure & Sense (Intermediate)

Explanation

Answer: A

PASSAGE

Researchers have observed that 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,✓ Correct
B. static;
C. static:
D. static

Detailed Answer Explanation

[Variation 3] 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.), C (A colon doesn't fit here; this is resuming the main clause.), D (Missing punctuation fails to close the parenthetical phrase.).