16.In order to make our city green, .

A.it is necessary to have planted more trees

B.many more trees need to plant

C.our city needs more trees

D.we must plant more trees

17. With a lot of difficult problems , the newly-elected president is having a hard time.

A.settled B.settling

C.to settle D.being settled

18. _______ such heavy pollution already, it may now be too late to clean up the river.

A.Having suffered B.Suffering

C.To suffer D.Suffered

19. Finding her car stolen, _______.

A.a policeman was asked to help

B.the area was searching thoroughly

C.it was looked for everywhere

D.she hurried to a policeman for help

20.Do let your mother know all the truth.She appears _______ everything.

A.to tell B.to be told

C.to be telling D.to have been told

21. I really appreciate _______ to relax with you on this nice island.

A.to have had time B.having time

C.to have time D.to having time

22.The bell _______ the end of the period rang, _______ our heated discussion.

A.indicating;interrupting B.indicated;interrupting

C.indicating;interrupted D.indicated;interrupted

23.Fishing is his favorite hobby, and _______.

A.he'd like to collect coins as well

B.he feels like collecting coins, too

C.to collect coins is also his hobby

D.collecting coins also gives him great pleasure

24._______ late in the afternoon, Bob turned off the alarm.

A.To sleep B.Sleeping

C.Sleep D.Having sleep

25.One learns a language by making mistakes and _______ them.

A.correct B.correcting

C.corrects D.to correct

26. Sandy could do nothing but _______ to his teacher that he was wrong.

A.admit B.admitted

C.admitting D.to admit

27.In order to improve English, _______.

A.Jenny's father bought her a lot of tapes

B.Jenny bought a lot of tapes for herself

C.a lot of tapes were bought by Jenny

D.a lot of tapes were bought by Jenny's father

28.Mr.Reed made up his mind to devote all he had to _______ some schools for poor children.

A.set up B.setting up

C.have set up D.having set up

29. _______ from heart trouble for years, Professor White has to take some medicine with him wherever he goes.

A.Suffered B.Suffering

C.Having suffered D.Being suffered

30. I've worked with children before, so I know what _______ in my new job.

A.expected B.to expect

C.to be expecting D.expects