A、Buy a used bicycle. B、Buy a racing bicycle. C、Replace the tires on his bicycle. D、Sell his old bicycle to the shop. A

W: Hi, John!
M: Oh. Hi, Laura. What’re you doing here?
W: Uh... I’m usually here on weekends. It’s my dad’s shop. So... you’re looking for a bike?
M: Yeah. Now that the weather’s warming up, I thought I’d get some exercise--instead of taking the bus all the time.
W: Well, you came to the right place. Do you know what you’d like?
M: Well, I don’t want a racer or a touring bike or anything. Mostly I’ll just be using it to get me back and forth from work.
W: How far is that?
M: About four miles.
W: Are there a lot of hills on the way?
M: Some, I guess. But... uh... maybe I should just tell you up front that I’ve only got a hundred and fifty dollars. Can I get anything decent for that?
W: Well, you’re not going to get anything top-of-the-line--but we do have a few trade-ins in the back that are in good condition.
M: That sounds good.
W: And you’re right, for the kind of riding you’re going to be doing, the most important thing is comfort. You want to make sure it’s the right height for you. Follow me and I’ll show you what we’ve got.
Q. 27. Why is Laura at the bicycle shop?
Q. 28.Why does John want to buy a bicycle?
Q. 29.What does Laura suggest that John do?
Q. 30.What does Laura say is most important about a bike?