II. 单项选择(共15题, 每小题1分, 满分15分)
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. Having a trip abroad is certainly good for the old couple, but it remains ______ whether they will enjoy it .
A. to see B. to be seen C. seeing D. seen
