( )I saw _____ boy walking across _____ street today.
()你要问路,就要先对对方说:__________ A. Excuse me. B. Can I help you ?
()Mike: Good afternoon, Mrs. White! Mrs. White:
()Sarah: Good morning, Mr. Black! Mr. Black:
()Mrs White: Hello, Mike. Mike:
()Sarah: Bye, Wu Yifan. Wu Yifan: