12.　 A happy family provides a loving _________ (环境) for its children.

11.　 The experience was good _________ (准备)for a career in the film industry.

10.　 All the morning he has been practicing _______ (介绍)himself because some VIP will attend the meeting.

9.　　　 The band play many songs, i______ some of my favorites.

8.　　　 You will be c______ with the best athletes in the world in the Olympics.

7.　　　 We all think that it is i________ to interrupt others when they are talking.

6.　　　 You have to o____ the rules if you want to live here.

5.　　　 Can you explain the causes and e_______ of all these?

4.　　　 Some rich women like wearing ________ (裘皮) coats.

3.　　　 The polluted air in the city is badly ________(危及)the health of the residents.