21.I have bought the bike for half a year.　

答案：bought→had

20.四千万来自贫困家庭的孩子仍然需要帮助。　

Forty 　　　　children 　　　　poor families still 　　　　help.

答案：million;from;need

19.我们已经建立了许多学校并且培训了大量老师。　

We have 　　　　many schools and 　　　　a lot of teachers.　

答案：built;trained

18.因为希望工程，数千名孩子有了更好的生活。　

　 　　　　　　　　Project Hope,　　　 　　　　　　　　　have better lives.　

答案：Because of;thousands of children

17.在希望工程的帮助下，现在他们能上学了。　

Now they can 　　　　　　　　school 　　　　the 　　　　　　　　　　　　Hope.　

答案：go to;with;help of Project

16.她的父母想要她退学。　

Her　　　 　　　　　　　　　　　　　　　　　out of school.　

答案：parents want him to stop

答案：don’t think;has seen

15.They flew to Shanghai once a month.(对画线部分提问)　

　 　　　　　　　　　　　　they fly to Shanghai?

答案：How often? did

14.I think Wang Fei has seen the film.(改为否定句)　

13.My friend wrote three letters last Sunday.(用since last Sunday代替last Sunday改写?句子)?　

My friend 　　　　　　　　three letters since last Sunday.　

答案：has written

12.Miss Zhang has studied English for three years.(改为同义句)　

Miss Zhang 　　　　　　　　　　　　English three years ago.

答案：began to study