从A、B、C、D四个选项中，选出可以填入空白处的最佳选项，并标在试卷的相应位置。
21. Rather than ________ on a crowded bus, he always prefers ________ a bicycle.
A. ride; ride B. riding; ride C. ride; to ride D. to ride; riding
22. Mr Li no longer smokes now because his wife _____ him to give up smoking last year.
A. suggested B. advised C. persuaded D. told
23. I like getting up very early in summer. The morning air is so good __________.
A. to be breathed B. to breathe C. breathing D. being breathed
24. --I’m going to the States?
--How long ___ you___ in the States?
A. are; stayed B. are; staying C. have; stayed D. did; stay
25. After the fighting, the enemy ____.
A. gave up B. gave out C. gave off D. gave in
