Could there be green plants on Mars?(火星)

　　There was a time when people told stories and made jokes about little green men who lived on Mars. Today, we know there are no little green men on Mars. But some scientists believe that there may be some kind of green plant growing there.

　　Mars has seasons like those on Earth. But each season on Mars is longer than an Earth season. Mars takes 687 days to move around the sun－almost twice as long as(长达) nearly 6 Earth months.

　　Pictures of Mars show a change of colour as the seasons change there. Some scientists believe this colour change may be caused(引起) by plants that grow thick as the seasons turn warm. Other scientists believe the colour change may be caused by giant(巨大的) dust storms. We will not know which scientists are right until the day we land on Mars.

根据短文内容，选择正确答案

1．Mars has ________ like those on Earth.

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2．On Mars, a season lasts for nearly ________.

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3．It takes Mars ________ it takes Earth to move around the sun.

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A．the same time as

B．almost twice as long as

C．a much shorter time than

D．three times as long as

4．The change of colour on Mars may be caused by ________.

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A．giant dust storms

B．spacecraft(宇宙飞船) landing on Mars

C．the short seasons on Mars

D．green plants

5．Which of the following is true?

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A．There is no life on Mars.

B．Scientists agree that we will never be able to land on Mars.

C．There are many questions still to be answered about Mars.

D．There are green plants on Mars.