Question

Choose the option that completes the sentence correctly.

He kept on _____ at the door till I opened it.

• A. To knock
• B. Knocking
• C. At knocking
• D. Knock

Answer 1

The correct option is B Knocking

Here, options A) to knock and C) at knocking can be eliminated because they are grammatically incorrect in the context of the sentence.

From the phrase 'kept on', we may infer that the act of 'knocking' continued. Thus, we need to use the continuous tense. So, Option D) knock is wrong since it is in the simple present tense. Therefore, the correct answer is B) knocking.