根据对话内容从方框内所给的选项中选出最佳答案，使对话完整，符合逻辑，句义通顺。注意：有多余选项。

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

B: Yeah. 1.______

A: Nervous about what?

B: I don’t know many of the customs and manners in the USA. 2.______

A: Sure.

B: 3._____

A: Well, it’ s important to be on time when you’re invited for dinner. 4._____ Americans expect their guests to be on time.

B: Then how long may I stay there?

A: 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.

—_______ do you usually go to school?— On foot.

A. What         B. When              C. Why.             D. How

-______ hard work you have done!

   -It’s very kind of you to say so.

   A. What            B. How             C. What a           D. How a

More and more Americans are going to work by bike. Do you know why more people are  41   bikes to work? We can answer the question in  42  ways. First, bikes don’t need gasoline (汽油), so it takes  43  money to use them. Second, a bike doesn’t  44 much space (空间), so it is  45 to find a                   place for it. And riding a bike is good for one’s  46 . People often drive their  47 to offices or to shops, but now people think riding bikes is a good way of doing sports.

That’s  48  more Americans are now riding to work  49  bike, and they are  50  their own cars at home.