21. Keep off _____ animal, it’s angry and so dangerous.

           A.  a                         B.  the             C.  an                  D./

22. Look! The light in the room is on. She ______ to bed.

     A. can’t have gone             B. mustn’t have gone     C. mustn’t go          D. hadn’t gone

23. He came back earlier than ________.

     A. being wanted               B. had hoped     C. was expected        D. expected

24. Linda was very busy when we went to see her yesterday. She _____ for an exam.

     A. studied                B. was studying      C. had studied     D. has studied

25. That’s the best way we should think of ______ the dying soldier.

A. helping                B. saving              C. operating             D. to save