装有两节新干电池的手电筒，它的电压是______V；家庭照明电路电压是_____

根据对话内容，从方框内所给的选项中选出最佳选项，将其答案的序号写在方框下面的横线上,选项中有两项为多余项。
A: You must be really excited about leaving for America tomorrow, Li Ping!
B: Yeah.小题1:______
A: Nervous about what?
B: I don’t know many of the customs and manners in the USA.小题2:______
A: Sure.
B: 小题3:______
A: Well, it’s important to be on time when you’re invited for dinner.小题4:______ Americans expect their guests to be on time.
B: Then how long may I stay there?
A: 小题5:______ Or you seem to have come only for the meal.When your friends seem to be getting tired and running 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.

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.