3

Set 7: Form, Structure & Sense (Advanced)

Explanation

Answer: B

PASSAGE

The phenomenon, observable only under specific atmospheric _______ has been documented fewer than a dozen times in recorded history.

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

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

Detailed Answer Explanation

This question tests your understanding of sentence function and text organization. The participial phrase 'observable only under specific atmospheric conditions' is parenthetical. A comma closes this phrase before the main verb 'has been documented.' 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:

• "The phenomenon, observable only under"

• "has been documented fewer than a dozen times"

Why others are wrong: D (A colon doesn't fit for closing a participial phrase.), A (A semicolon is too strong for closing a participial phrase.), C (Missing punctuation fails to close the parenthetical phrase.).

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