单项选择题

[听力原文]9-10
W: Now, Mr. Zhang, did you see the accident clearly
M: Oh, yes. I was standing outside the department store.
W: Do you know what time it happened
M: Yes, it was 5:40 by my watch.
W: Good. Now, was the truck going fast
M: Yes. Well, perhaps the driver thought they were going to change to green. But they were red.
W: Are you sure, Mr. Zhang
M: Yes, absolutely sure.
W: Well, thanks a lot, Mr. Zhang. Good-bye.
M: Good - bye.

What are the two speakers talking about（）

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