A. It's good to stay at home for you.      

     B. After the meal, don't leave at once. 

     C. Could you give me a hand?

     D. What rules do they have in America?

     E. But I'm a bit nervous.

     F. You're supposed to leave before the meal.

     G. It's impolite to arrive late.

A: You must be really excited about leaving for America tomorrow, Li Ping!

B: Yeah.

A: Nervous about what?

B: I don't know many of the customs and manners in the USA. 

A: Sure.

B:  

A: Well, it's important to be on time when you're invited for dinner.Americans expect their guests to be on time.

B: Then how long may I stay there?

A: Or you seem to have come only for the meal.  When your friends seem to be getting tired and run-ning out of things , it's time to leave. The next day, call or write a thank-you note to say how much you enjoyed the evening.