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 yesterday.
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.

A. don't
B. be
C. aren't
D. not be