Choose the part of the sentence that is grammatically incorrect:
The thief took towards / his heels / on seeing / the Police-van arrive.

Question

Accepted Answer

The grammatically incorrect part of the sentence is "The thief took towards." Here's why:

*   **Why Option 1 is incorrect:** The phrase "took towards" is redundant and grammatically incorrect in this context. The correct idiom to describe someone running away quickly is "took to his heels." "Took" already implies movement in a direction, so adding "towards" is unnecessary and creates an awkward construction. The correct phrasing would be "The thief took to his heels."

*   **Why Option 2 is correct:** "his heels" is part of the correct idiom "took to his heels," which means to run away quickly. There is no grammatical error in this phrase.

*   **Why Option 3 is correct:** "on seeing" is a grammatically correct prepositional phrase that introduces the reason for the thief's action. It correctly indicates that the thief ran away *because* he saw the police van.

*   **Why Option 4 is correct:** "the Police-van arrive" is grammatically correct in this context. "Arrive" is used as a bare infinitive after the verb of perception "seeing." The entire phrase "on seeing the Police-van arrive" functions as an adverbial phrase modifying the verb "took."