用单词的适当形式填空。

1. How many ________ (三明治) would you like?

2. John is a ________ (天赋的) actor.

3. I spent an hour ________ (打扫) my room.

4. - Who ________ (写) this piece of music? -Mozart did.

5. I live in a town ________ Alice Springs. (叫做)

6. Look at the dark clouds in the sky. It ________ (下雨) soon.

7. In my family Dad is ________ (忙碌).

8. English is a useful ________ (外国的) language in our country.

9. Li Ying is not as ________ (幽默) as Li Li.

10. Maria won the ________ (一) prize in yesterday's swimming competition.

在组装活塞环时，应活塞环标记面朝上，第一道活塞环的开口方向，应（），各道活塞环的开口方向应互呈90°或180°。

A．朝向发动机作功时的受力面

B．应背向发动机作功时的受力面

C．没有特殊规定，只要活塞环的透光度和端隙符合车型技术要求即可