用括号内所给动词的适当形式填空。

1. I’ll tell our monitor the good news as soon as he ________ (come) back to school.

2. It was a pity that you _________ (not attend) the meeting last Friday afternoon.

3. We should think about what we can do ________ (keep) animals and plants from becoming endangered.

4. On May 12, 2008, sichuan __________ (hit) by a strong earthquake which killed many people and destroyed many buildings.

5. Playing computer games is delightful, but _______ (spend) too much time on it may do harm.

6. Today, to hold the Olympic Games __________ (consider) as a rich prize for a country.

7. Many changes ________ (take) place in our daily life since the invention of the computer.

8. The policeman said that he __________ (see) a Young Pioneer help an old woman cross the road the day before.

9. Our Maths teacher __________ (prepare) the new lesson with other teachers in the office from 2 to 4 yesterday afternoon.

10. The first step towards ________ (protect) the environment is to try to throw away less rubbish.