题目内容：

    For centuries, humans have wondered whether there is life on Mars. Scientists have asked why Mars is losing its atmosphere. Last week, the question was answered with a song. “The answer is blowing in the wind,” said Michael Meyer, taking a line from a Bob Dylan song. Meyer is the lead scientist for NASA’s Mars Exploration Program. It turns out that solar winds from the sun are slowly blowing away Mars’ atmosphere.

Today, Mars has a thin atmosphere. It is cold and dry, with a desert-like environment. Jakosky says it used to be much more different. “When we look at ancient Mars, we see a different type of surface. One that had valleys looked like they were carved by water, lakes that were standing for a long period of time. We see an environment that was much more able to support liquid water.”

Recently they found a kind of liquid water that flows with salt down a mountain area of the planet. But it is not always there. Scientist Michael Meyer describes what they found: “We’re seeing water, with the salt that’s able to flow down the sides of the cliff. Why is this important? That means there is water on Mars, on the surface of Mars today.”

Scientists already knew that ice exists on Mars. So why is it important to find liquid water? Meyer explains: “It means that we have a resource. And when we're looking at sending humans to Mars, water is one of the key things that we need to have, not only for astronauts to drink, but also to make oxygen, to make fuel.”

Sending humans to Mars is still in the distant future. NASA is aiming for the 2030s. Both US government and private industries are developing rockets and spacecraft to get people to Mars.

1.Why is the atmosphere of Mars disappearing?

A.Because Mars doesn't have water to keep the atmosphere.

B.Because the atmosphere is affected by the earth.

C.Because the atmosphere is blown away by the solar wind.

D.Because Mars has no condition to make the atmosphere exist.

2.Which of the following are the functions of the water on Mars?

①Taking shower.     ②Drinking for astronauts.     ③Making fuel.

④Watering plants.    ⑤Producing oxygen.      ⑥Washing clothes.

A.②④⑤ B.①③④⑤ C.②③④⑥ D.②③⑤

3.What can we infer from the passage?

A.Whether water exists on Mars or not isn’t important to humans.

B.Mars’ atmosphere has changed a lot since it existed.

C.We can successfully send humans to Mars from now on.

D.Water can not appear on Mars because of its thin atmosphere.

4.Which of the following can be the best title of the passage?

A.Mars Has Conditions to Support Humans

B.Mars Is Strongly Influenced by the Solar Wind

C.Mars and Its Thin Atmosphere

D.Water Does Exist on Mars