罗马帝国的缔造者是伯利克里。（   ）

读“七大板块与主要火山、地震带的分布”，回答下列问题．

⑴Where are your parents?____                           A. Yes, I'd like some fruit.

⑵Is your brother sleeping in the room?____      B. They are at home. 

⑶Can I help you?____                                         C. She's playing the piano.

⑷Would you like some fruit?____                       D. No, I'm not.

⑸Can you see the red light?____                        E. She's singing.

⑹What is Helen doing?____                                F. Yes, please.

⑺Are you busy?____                                           G. No, I can't.

⑻What is she doing in the music room?____     H. No, he isn't.

乒乓球漂浮于水面上，乒乓球所受浮力的施力物体是（　　）