240.

M: Hi, Mum.

W: There you are. I'm getting worried. It's so late.

M: Yes. I ran into Linda and we went to a pub. She told me a funny thing.

W: Oh? What was that?

M: Well, she was driving home after work, and she suddenly saw an old lady on her hands and knees in the middle of the road.

W: Really?

M: Yes, Linda was so shocked that she stopped suddenly and the car behind crashed into hers.

W: Was her hurt?

M: No.

W: And what was the old lady doing?

M: I am just coming to that. So Linda got out of her car and saw the old lady pick up something and walk away.

W: Lucky indeed. Linda didn't run her over.

M: Then a policeman came. But he didn't believe what Linda said.

W: Well...

M: Luckily there was a witness, a man waiting for a bus. He saw it all. Guess what the old lady was doing?

W: I haven't the slightest idea.

M: She was looking for her gold tooth.

W: A gold tooth?

M: Yes, it fell out as she was crossing the road. The witness heard her saying, "Oh, my gold tooth..."

答案解析：

(1) 正确答案为B。根据I ran into Linda and we went to a pub. 我遇见了琳达，我们一起去了酒吧。可知，男子回家晚了是因为和琳达去了酒吧，因此B项正确。

(2) 正确答案为A。根据saw the old lady pick up something and walk away.看到那位老妇人捡起了什么东西然后离开了。以及后来说She was looking for her gold tooth.老妇人在找她的金牙。可推知，老妇人在马路中间找东西，因此A项正确。

(3) 正确答案为C。根据she stopped suddenly and the car behind crashed into hers.她急刹车，后面的车撞上了她的。可知，琳达发生了车祸，因此C项正确。

(4) 正确答案为B。根据Luckily there was a witness, a man waiting for a bus.幸好有一位目击者，有个男子在等公交车。可知，目击者是在车站等公交车，因此 B项正确。