4、等比数列的各项为正，公比满足，则的值为________．　

3、已知，　 则 的最大值是________．

2、已知集合，,则________．

1、的值为________．

20. The plan _____ just because people were unwilling to co-operate.

A. pulled downed　 　　　　 B. broke down　 　　　　　　　 C. turned downed　 　　　 D. put down

19. After graduation from college, Joe ____ for a year seeing the country before he went to work in his father’s business.

A. knocked about　　　　　 B. knocked over　 　　　　　　 C. knocked down　　　　　 D. knocked off

18. The hunter ____ down and ____ to the farmer that he had___ his gun against the tree.

A. lay, lied, laid　　　　　　　 B. lay, laid, laid　　　　　　　　　 C. laid, lay, lied　　　　　　　 D. laid, lied, lay

17. How did the accident_____________? 　

A. come out　　　　　　　　　 B. come along 　　　　　　　　 C. come about　　　　　　　 D. come across

16. The boys arguing over whether to play baseball or football finally ___ by voting.

A. reached goals 　　　　　 B. came to terms 　　　　　　 C. came to an end　　　　　 D. gave up

15. So many young men want to ___ writing.

A. take in　 　　　　　　　　　 B. take up　 　　　　　　　　　　 C. take over　　　　　　　　　 D. take off