II. 单项填空（每题1分，共15分）
21. I prefer working out the problem ________ someone else for help.
A. ask B. to ask C. asking D. to asking
22. -I haven't heard from Henry for a long time.
-What do you think ________ to him?
A. happening B. to happen C. has happened D. had happened
23. -David has made some mistakes in the test.
- _______
_ ,and ________ .
A. So he has; so you have
B. So has
he ;so
have you
C. So has he; so you have
D. So he has; so have you
24. -Which
book do
you want, the chemistry b ...