:高三英语阅读与理解训练题（20套）

:阅读理解训练题（二十）
At first sight the planet Mars（火星）does not appear very welcoming to any kind of life. It has very little oxygen and water, the temperature at night is below-50 degrees and winds of 100 miles （161 kilometres）per hour cause severe dust storms. However, the surface of the planet seems to show that water flowed across it at some time in the past, and it is believed that there is enough ice at the poles to cover the planet with water if it melted. Although there is no life on Mars now, some scientists think that there may have been some form of life a long time ago. At that time, the planet had active volcanoes（火山）; the atmosphere was thicker and warmer; and there was water. In fact, in some ways Mars may have been similar to Earth, where life exists.
 Some people believe that Mars could support life in the future if the right conditions were produced. The first step would be to warm the planet using certain gases which trap the sun’s heat in the planet’s atmosphere. With warmth, water and carbon dioxide（三氧化碳）, simple plants could begin to grow. These plants could slowly make Mars fit to live on. It is judged that the whole process might take between 100,000 and 200,000 years. In the meantime, people could begin to live on the planet in special closed environments. They would provide a lot of useful information about conditions on Mars and the problems connected with living there.
56．According to the passage, the planet Mars has noon it.
    A．wind          B．dust          C．mountains      D．animals
57．It is believed that on Mars now   .
    A．there is a large amount of ice at the poles. B．there is a thicker and warmer atmosphere
    C．there are some kinds of simple plants   D．there are so many active volcanoes.
58．What is the topic discussed in the second paragraph?
    A．Certain gases should be used to warm Mars. B．Plants should be grown to make Mars fit to live on.
    C．Mars could support life on right conditions in the future.
    D．People could live on Mars in special closed environments.