Fill in the blanks with the most appropriate words. He ____ me if I _____ a taxi yesterday.

The correct answer is: D. asked / had taken

The sentence is in the past tense, so we need to use past tense verbs. Option A is incorrect because “will ask” is in the future tense. Option B is incorrect because “ask” is in the present tense. Option C is incorrect because “is asking” is in the present continuous tense. Option D is correct because “asked” is in the past tense and “had taken” is in the past perfect tense.

The past perfect tense is used to talk about something that happened before another event in the past. In this case, the event that happened before is “he asked me”. The event that happened after is “I had taken a taxi”.

Here is a diagram that shows the time order of the events:

• Before: He asked me if I had taken a taxi.
• After: I had taken a taxi.

I hope this explanation is helpful!