题目内容：

“Stop! Stop！”

The police officer ran down the street as fast as he could. “Stop！” he said again. But it was no use. The car kept going. The officer said to himself, “They must be going ten miles an hour.”

There weren't many cars on the road in the early 1900s. Most people thought driving ten miles an hour was too fast for safety. And since police officers didn't have cars of their own, they could only run after speedsters(快速驾驶者).

The early cars were faster than the horse­drawn buggies(马车) that most people still used. And they frightened (使惊恐) the horses. One car maker tried to keep the horses cool. He made the car with the horse's head. He hoped real horses would think it was a horse and buggy. They didn't. It frightened them just as much.

The car with the horse's head wasn't the only early car that would look strange today. Some looked like buggies without a horse. Others had three wheels (轮子). A few even had their steering wheels (方向盘) in the back seat.

根据短文内容，回答下列问题。

1.What did the police officer ask the car to do?

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2.How many miles an hour did the police officer think the car travelled?

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3.Did people see lots of cars on the road in the 1900s?

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4.What did a car maker do in order to keep the horses cool?

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5.What does this passage mainly tell us?

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