6

Set 4: Form, Structure & Sense (Intermediate)

Explanation

Answer: B

PASSAGE

Researchers have observed that researchers have discovered that certain genes, when _______ correctly, can enhance a plant's resistance to drought conditions.

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

A. will express
B. expressed✓ Correct
C. expressing
D. are expressing

Detailed Answer Explanation

[Variation 3] This question tests your understanding of sentence function and text organization. 'When expressed correctly' is a reduced adverbial clause (from 'when they are expressed'). The past participle 'expressed' correctly forms this construction. 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:

• "certain genes, when _______ correctly"

• "can enhance"

Why others are wrong: A ('When will express' creates an awkward future construction.), C ('When expressing' suggests genes express themselves, but genes are expressed.), D ('When are expressing' is grammatically incomplete.).