21.Of all reasons for my decision to become a university professor, my father’s advice was most important one.
A.the;a B.不填；a C.不填;the D.the;the
22.The computer system suddenly while he was searching for information on the Internet.
A.broke down B.broke out C.broke up D.broke in
23.I hear boys in your school like playing football in their spare time, though others prefer basketball.
A.quite a lot B.quite a few C.quite a bit D.quite a little
