【正确答案】 D

【答案解析】[听力原文]
   M: Can you tell me something about the university shuttle bus system? This is such a large campus, and I have classes all over campus. I need to take the shuttle bus from one class to another, or I'll never make it on time.
   W: What do you need to know? I think it's a really great system.
   M: First of all, where does it go?
   W: The university shuttle bus system goes all over campus. It doesn't leave the campus; if you want to travel off-campus, you'll need to take the city bus system. But the university shuttle bus system will get you from one class to the next very efficiently.
   M: And how much does it cost?
   W: It's free, can you believe it? So you don't have to pay a cent to get all around the university campus.
   M: That's really great. And how do I catch the shuttle bus?
   W: Just look for one of the bright yellow shuttle bus signs, and go stand next to it. You can see the yellow shuttle bus signs all over campus. A shuttle bus will come along approximately every five minutes, so you shouldn't have to wait long.
   M: That all sounds good. Thanks for your help.
   W: No problem.
   What are the man and woman discussing?
选项全是名词短语，问对话主题的几率颇大。对话开头的第一句话就点出了答案所在，即D。如果实在没有听懂第一句话，后面还有机会听出答案，因为全文讲的都是the university bus system。