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) 正確答案為B。根據I ran into Linda and we went to a pub. 我遇見了琳達，我們一起去了酒吧。可知，男子回家晚了是因為和琳達去了酒吧，因此B項正確。

(2) 正確答案為A。根據saw the old lady pick up something and walk away.看到那位老婦人撿起了什么東西然后離開了。以及后來說She was looking for her gold tooth.老婦人在找她的金牙。可推知，老婦人在馬路中間找東西，因此A項正確。

(3) 正確答案為C。根據she stopped suddenly and the car behind crashed into hers.她急剎車，后面的車撞上了她的。可知，琳達發生了車禍，因此C項正確。

(4) 正確答案為B。根據Luckily there was a witness, a man waiting for a bus.幸好有一位目擊者，有個男子在等公交車。可知，目擊者是在車站等公交車，因此 B項正確。