19. have returned
20. have gone
21.had recieved
22. have answered
23kept

19. Since I left Venezuela six years ago, I (return)..have returned....................................to visit friends and family several time.
20. As soon as my parents came, we (go).....was going.................................out for dinner.
21. After ancient Greek athletes won a race in the Olympics, they (receive)....had received..................................a simple crown of olive leaves.
22. I (answer)....have answered.................................. all of the questions correctly since I began this exercise on verb tenses.
23. Although it was noisy, I (keep)......................................on studying.
24. No matter what kinds of exercises he had taken, he (still/ put)......................................on weight.
25. I got a sore throat because I (speak).......have spoken...............................for 3 hours.
26. Because she felt tired, she (go)........went.............................. to bed early.
27. I don’t like to speak English because I (be)........am..............................afraid of making mistakes
.28. I whispered because I (not/ want)......................................to disturb anyone

1.returned
2.had gone
3.had received
4.had answered
5.kept
6.had still put
7.have spoken
8.went
9.was
10.didn't want

Đối vs một đứa lớp 6 như mik thì phải toát mồ hôi mới làm ra:
19. Returned
20. Went
21. Have received
22. Have answered
23. Keep