用所给词的正确形式填空。

1. It is interesting _________ (know) something about animals.

2. __________ (not open) the door. It is cold outside.

3. She can work out the difficult question _________ (easy)

4. Please keep ___________ (quietly) in the reading - room

5. —Where is my cup?  

   —__________ (you) is over there.

6. What about _________ (go) fishing with us tomorrow?

吊缸发现燃烧室零件表面有水锈时，表明（）产生穿透性裂纹。

A.活塞

B.气缸

C.喷油器

D.气缸或活塞