学进去

Scientists are very interested in the Universe，and they always want to know more about it. Years ago they knew many things about the moon. They knew how big it is and how far away it is from the earth. But they wanted to know more about it. They thought the best way was to send men to the moon. The moon is about 384,000 kilometers away from the earth. A plane cannot fly to the moon because the air reaches only 240 kilometers away from the earth. But something can fly even when there is no air. That is a rocket(火箭)
How does a rocket fly? There is gas（气体） in the rocket. When the gas is made very hot inside the rocket, it will rush out of the end of the rocket, so it can make the rocket fly up into the sky. Rockets can fly out into space. Rockets with men in them have been to the moon. Several rockets without men in them have flown to another planet(行星) much farther away than the moon. One day, rockets may be able to go to any place in space.
1．Scientists knew ____________ the moon is.
A: how far    B: how big    C: how old    D: both A and B
2．The earth is about 384,000 kilometers away from the _____.
A: space    B: universe    C: sun   D: moon
3．A plane cannot fly to the moon because ___________
A: there is no air above 240 kilometers away from the earth.
B: there is no gas in the plane
C: the plane is not strong enough
D: the plane can not fly a long way
4．The hot gas in the rocket is used for___________
A: keeping the air in the rocket fresh(新鲜的)
B: Keeping the men in the rocket warm
C: making the rocket fly up.
D: cooking food for the men
5．What is the writer’s attitude(态度) to the universe’s future.
A: Realistic(现实的)        B: Imaginative(幻想的)
C: Confident(有信心的)      D: Sad