20、___ it carefully can we hope to find a way to solve the challenging problem

A．When we observe                                   B．When to observe

C．That we should only observe                   D．Only by observing

19、Does anybody know how it _____ to live without eating for so many months

A. keeps       B. manages       C. succeeds     D. tries

18、--- How about seeing the new movie at the theatre tonight?

---- _____, but I’ve got to go over my notes for tomorrow’ exam.

A. All right       B. Sounds great    C. I can’t     D. No, I am terribly sorry

17、As time went by, the plan they stuck to______ fairly practical.

A. proving        B. proved         C. was proved     D. be proved

16、What a pity! I missed meeting my boss at the airport because my car was _____in the traffic jam.

A. broken up       B. broken down      C. held up         D. kept up

15、The new law to punish the drunk driver will come into        on the day it passes.

A．existence                    B．use                  C．service                   D．effect

14、Our house is on the top of the hill, and in winter the winds _____ be pretty cold

A. must      B. ought to        C. can           D. need

13、Was it six years ago, when he came to China for the first time, _____ he  began to learn Chinese?

A. where     B. how          C which          D. that

12、 Is the meeting held in Room 405 or 406?

-- It should be 405. But I hear that it ______till tomorrow.

A. was put off                   B. will put off

C. has been put off            D. is put off

11、The scientist is to attend the meeting ______ in the Great Hall of the People.

A. to be having     B. to be held      C. to hold      D. held