情景交际。

Dave的妈妈在邀请她的朋友Mary来参加晚会，用A-F来表示她们的对话顺序。

( ) 1. That's grert!I can come at seven o 'clock.

(     ) 2. Mary,can you come to my party on Saturday?

(     ) 3. When is it?

(     ) 4. Well,the party is on Saturday evening.

(     ) 5. It's at seven o'clock.

(     ) 6. I'm sorry, I can't,I have to visit my uncle on Saturday afternoon.

轴承零件表面呈分散或群集状的细小坑点称为（）。

A.麻点

B.辗皮

C.剥离

D.擦伤