Here are the correct answers for the sentences:

21. It didn’t take long to **A. come down** the office.
22. The hospital is **A. carrying out** tests to find out what is wrong with her.
23. I feel like I’m coming **D. down** with a cold.
24. It’s great to **A. hang up** with people better than you.
25. I am trying to cut **A. down** caffeine.

So, the complete answers are:
21. A
22. A
23. D
24. A
25. A