Question

--- Excuse me. Did you see Tom just now?

--- I saw him _______ the building and go upstairs.

1. A.
   to enter
2. B.
   enter
3. C.
   entering
4. D.
   entered

Answer 1

B
点拨：题意是“请问，刚才你看见汤姆了吗？”“我看见他进了这座楼，上楼了。”此题考查see sb. do sth.与see sb. doing sth.的区别。前者指动作的终结，后者指动作的持续，此题是动作的终结。选项A和D不符合以上两种结构，选项C是指动作的持续。