Introduction / Context:
The test here is idiomatic determiners with “working knowledge”. Books typically address “your” or “the reader’s” working knowledge. The phrase “increase a working knowledge” is odd because “a” does not anchor whose knowledge is being increased; the sentence needs a possessive or a definite reference to sound natural and precise.
Given Data / Assumptions:
- Purpose clause: “designed to increase …”.
- Target noun phrase in C: “a working knowledge of …”.
- Audience is general readers, so a second-person implied possessive is standard in educational copy.
Concept / Approach:
- Preferred collocation: “increase your working knowledge of …” or “increase the reader’s working knowledge of …”.
- Using bare “a working knowledge” without a possessor makes the claim grammatically awkward.
Step-by-Step Solution:
Replace the indefinite article with a possessive determiner.Correct version: “This book is designed to increase your working knowledge of spoken and written English.”All other parts remain unchanged.
Verification / Alternative check:
Compare publishing blurbs: they routinely use “your working knowledge”.
Why Other Options Are Wrong:
A, B, D: Grammatically sound as framed.E: Not applicable because C contains the idiomatic error.
Common Pitfalls:
Overusing the indefinite article with abstract count nouns that need a possessor.
Final Answer:
a working knowledge of
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