The question whether there is life on Mars (火星) has made the public think a lot for more than a century. The closest look showed Mars to be a dusty, cold world, covered by air too thin to breathe. A British spaceship and Europe's Mars spaceship plan to land on Mars or enter orbit (轨道) around it. One of the NASA’s (美国宇航局) spaceships is expected to land on January 3, the other is going to land on the opposite side of Mars on January 24. Since 1960, over twenty spaceships sent to Mars have failed. Most have been lost on flying up or landing because those are the most difficult times of any flights. Scientists wanted to find out whether there was water in Mars. In October, a team of scientists reported that Mars had been a dry wasteland. But weeks later, a second team reported differently that they had found some marks showed clearly that they were made by the rivers. Such marks told us that Mars was a warmer place billions of years ago — just as life first appeared here on Earth. Scientists at once raise a question: if what they said is true, what happened on Mars? Then what about the earth?
小题1:Which is right about Mars?
A．It’s cold without dust.
B．There is no water or air.
C．It’s warm with some thin air.
D．It’s a dusty, cold world almost without air.小题2:Two NASA’s spaceships _______________.
A．will land on the different sides of Mars
B．will land on the same day
C．will enter orbit around Mars
D．will land with a man小题3:The most difficult times of a flight are _______________.
A．taking off
B．flying up and arriving
C．entering the orbit and landing
D．leaving the earth and entering the orbit小题4:A team of scientists reported that there might be_____________ in Mars.
A．nothing but air
B．nothing
C．water billions of years ago
D．thick air and lakes小题5:What are scientists worried about when they raise the question?
A．Life disappeared on Mars.
B．Spaceships can’t land on Mars.
C．The air on the earth gets less and less.
D．The earth might be changed like Mars
此式在统计学中采用的单侧置信概率为（）。