20．We met _____ and have become good friends since then.

A. by mistake　 　　 B. by accident　 　 C. by ourselves　 D. by the way

19．_____ your advice, I’m sure to consider it and give you reply in time.

A. In spite of　 　　　 B. But for　 　　　　　 C. Because of　 　 D. As for

18．--- Tom has a lot of parties recently.

---Yes, that may ____ why he didn’t do well in the test.

A, sum up　 　　　　　 B. add up to　 　　　　　　　 C. account for　 　　 D. make sense of

17．I’m ____a diet, since I put ____ weight easily.

A. in; on　 　　　　　　 B. on; in 　　　　　　　　　　 C. in; in　 　　　　　 D. on; on

16．He is heavily ____ now, so he can’t pay for a new house.

A. out of debt　 　　 B. get into debt　 　 C. in debt　 　　　　 D. get out of debt

15．---Tom is never late for work. Why is he absent today?

---Something ________ to him.

A. must happen 　　　　　　　　　　　　 B. should have happened　

C. could have happened 　　　　　　　 D. must have happened