题目内容：

Scientists at the California Institute of Technology (Caltech) have reported evidence that Mars was warmer and wetter long ago than it is today.  The Caltech scientists say they have directly established the temperature of Mars four billion years ago. At least, they established the surface temperature on part of the planet at that time. The researchers say it is the first such evidence to be discovered and presented.

The Caltech scientists say carbonate（碳酸盐）minerals formed on Mars at about eighteen degrees Celsius. They reached the finding after studying a meteorite（陨石）that had its beginnings near the Martian surface.

Today, the average temperature on Mars is sixty-three degrees below zero Celsius.

The finding was reported on the website of the National Academy of Sciences. Caltech Assistant Professor Woody Fischer helped to prepare the report. He says eighteen degrees Celsius is not especially cold or hot. He says this makes the finding extremely interesting. Knowing the temperature can give scientists an idea of the climate on Mars long ago. It can also help them decide whether the planet had liquid water. Spacecraft orbiting Mars have shown what appear to be rivers, lakebeds and mineral deposits. These pictures suggest that, at one time, water did flow there. Mars Rover vehicles and other spacecraft have proved the information.

The meteorite the scientists examined is one of the oldest known rocks in the world. It is called the Allan Hills meteorite. Its name came from the place in Antarctica where it was found in 1984. The meteorite is believed to have blown loose from the Mars' surface when another space rock struck its "home."

1.The underlined word “establish” in Paragraph 1 probably means “___________”.

A. to set up 

B. to make people accept a belief

C. to discover or prove

D. to start having a relationship with others

2.How did the scientists reach the finding?

A. By studying Allan Hills meteorite.

B. By using spacecraft orbiting Mars.

C. By studying minerals gathered on Mars.

D. By studying a meteorite on the Martian surface.

3.According to the fourth paragraph, what have spacecraft orbiting Mars done?

A. Measuring the temperature of Mars.

B. Taking photos of the surface of Mars.

C. Finding that there is water flowing on Mars.

D. Proving where human beings will probably land on Mars.

4.Where can we most probably read this passage?

A. In a biography of scientists.B. In a geography magazine.

C. In an environment report.D. In a science report.