从A –G选项中选出能填入空白处的最佳选项补全对话。（选项中有两项是多余的。）

A: The bus is coming! B: Take the No.67 bus over there. C: Why do they wear helmets? D: They are from my cousin in the USA. E: A life jacket. F: You must wait for a minute. G: It's a helmet.

Mike: Excuse me, Mr. Smith. How can I get to Fuxing Hospital?

Mr. Smith:.

Mike:Thanks. Wow! So many pictures of bikes!

Mr. Smith:

Mike.What's this?

Mr. Smith:In the U.S.A. people on bikes must wear one.

Mike:

Mr. Smith: Because the helmets can protect（保护）their heads.

Mike: I see.Bye, Mr. Smith.

Mr. Smith: Goodbye.