Ⅰ. 单句语法填空
1. For me this is one of the most rewarding trips that I have made (make) in my life.
2. Sara has been (be) to the Summer Palace twice.
3. Susan had quit her well-paid job and was working as a volunteer in the neighborhood when I visited (visit) her last year.
4. Recently I have learnt(learn) how to get along with that stubborn boy.
5. We entered(enter) the school 3 months ago, which means we have been high students for a season or so.
6. The books went missing in the library and nobody has seen (see) them ever since.
7. It has been 20 years since they came (come) to China.
8. It is the first time that an agreement has been reached (reach) between the two countries.
9. He is the only one of the students who was sent(send) to study abroad 3 years ago.
10. So far this year we have seen (see) a fall in housing prices by between 3% and 5%.
11. With the help of high technology, more and more new substances have been discovered (discover) in the past decades.
