31.　　　 　many times, he still couldn't understand.　　　　　　　 　A.Having been told　B.Having told 　C.He having been told 　 D.telling

30.Many things ____　impossible in the past are very common today.　　 　sider　sidering 　sidered　 D.be considered

29.The students in the university are all taking courses ____　a degree.　　　　　　　　　　　　　　　　　　　　　 　ing to　B.going to　 C.leading to　　 D.turning to

28. ____different kinds of pianos, the workers farther improved their quality　　　　　　　　　　　　　　　　　　　　　　　 　A.To produce　 B.Being produced 　C.Produced 　 D.Having produced

27.A person ______a foreign language must be able to use the foreign language 　　　　　all about his own.　　　　　　　　　　　　　　 　A.to learn, to forget 　B.learning, to forget 　C.to learn, forgetting　 　D.learning, forgetting

26.The wallet 　____　several days ago was found ____　in the dustbin outside the building.　　　　　　　　　　　　　　　　　　　 　A.stolen, hidden　　B.stealing, hiding 　C.stealing, hidden　 D.stolen, hiding

25.Lessons 　____　easily were soon forgotten.　　　　　　　　 　A.to learn　　B.learn　 　C.learned　　　 D.learning

24.The ground is 　____with 　____leaves.　　　　　　　　 　A.covering, falling 　 B.covered, falling 　C.covered, fallen 　 D.covering, fallen

23.The library's study room is full of students 　____　for the exam. 　A.busily prepared　 B.busy preparing 　C.busyly prepare 　 D.are busily preparing

22.The scientists were waiting to see the problem ____　.　　　　 　A.settle　　 B.settled　　 C.to settle　　 D.settling