题目内容：

“Global warming could make humans shorter,” warn scientists who claim to have found evidence that it caused the world's first horses to shrink(收缩) nearly 50 million years ago. In fact, a team from the universities of Florida and Nebraska says it has found a link between the Earth heating up and the size of mammals – horses, in this case.

The scientists used fossils to follow the evolution of horses from their earliest appearance 56 million years ago. As temperature went up，their size went down, and vice versa（反之亦然）;“ At one point they were as small as a house cat,” said Dr Jonathan Bloch, curator（博物馆长） of the Florida Museum of Natural History, which was quoted by the "Daily Mail" as saying.

The scientists say that the current warming could have the same effect on mammals and could even make humans smaller."Horses started out small, about the size of a small dog . What's surprising is that after they first appeared, they then became even smaller and then dramatically increased in size, and that exactly corresponds to the global warming event, followed by cooling”

"It had been known that mammals were small during that time and that it was warm, but we hadn't realized that temperature specifically was driving the evolution of body size," Dr Bloch said in the "Science" journal.

1.How did scientists find out the horses’ earliest appearance millions of years ago?

A. searching the data on the net

B. sorting through the pictures of ancient times

C. using fossils to follow the evolution

D. analyzing the related images

2.What can we infer form the passage?

A. As temperatures went up, horses dramatically increased in size

B. The temperature has no effect on mammals’ evolution

C. As temperatures went up, horses’ size went down

D. In history, it used to be warm at early times , followed by a certain period of sharply cooling down.

3.Which is the most closest meaning to the underlined words most probably mean _______.

A. react to                B.  be contradictory to 

C. be consistent with         D.  differ from

4.What is the best title of the passage?

A. Global warming is to disappear

B. The temperature on earth is to decrease

C. Global warming makes human shorter

D. Mammals are dying out.