The rockets take astronauts and man-made satellites into space. The satellites are used for communication, weather monitoring and research. But how do satellites stay up without falling down?
There are two opposite forces (力量) acting on the satellite. One of them is the force of gravitation (地心引力), which tries to pull the satellite towards the earth. The other force is created by the rotation (旋转) of the satellite around the earth. This force tries to take the satellite away from the earth. With these two forces, the satellite goes round and round. The gravitational pull of the earth (the force which pulls everything towards the ground) is like a rope which keeps the satellite from flying away.
Everything that goes up has to come down. It is only a matter of time before a satellite comes back to the earth. As time goes by, the satellite loses its speed, which makes the gravitational pull stronger than the force pulling it away. This makes the satellite crash (坠落) down to the earth.
【小题1】Which of the following uses of satellites is NOT mentioned?

 
“Low *carbon” becomes the most popular words these days because more and more people pay attention to our environment. Not only China but all other    1   concentrate on the topic of “low carbon”. Low carbon life    2    a kind of lifestyle in which people do their best to use less energy. The purpose of the lifestyle is to push us to    3    the environment.
Because of the fast increase of population and human *desire, the human living environment, health and safety are    4    worse and worse. So we can say, the lifestyle is becoming the killer of the earth and human beings. Therefore, low carbon life is needed by man’s own health. So we should develop good    5    in our daily life. For example, when we go shopping, we’d better use    6    plastic bags. We should eat more    7    and less meat. As for clothing, we’d better buy the necessary clothes and not buy clothes with animal *leather. As for housing, when building a    8   , we must use green material; buy the lights that need less energy and remember to    9    the lights when not needed; put rubbish into different kinds and recycle the useful things, like bottles and paper. As for transportation, we can    10    if you go to the places near your house. For short trips, we can ride a bike instead of driving a car. Try to use public transportations. As for working, companies should    11    clerks to use e-mail, MSN and other ways instead of using paper. We use paper only when necessary. For using    12    : If you don’t use computer in a short time, you can change the computer into its “sleep”.
Besides, we should try    13    best to tell the people around us the importance of the low carbon lifestyle. And we can also ask them to    14    us to take the low carbon life, in this way, not only can we make our city better,    15    also it’s good for ourselves.
In all, it weighs greatly for all of us to put the low carbon lifestyle into practice.

We have always been interested in the moon. 2000 years ago people already knew it moved around the earth and where it would be in the sky at different times of the year. At that time, everything about the moon was learned by watching it carefully in the sky.
When scientists could use telescopes(望远镜) to study the moon more closely, their ideas began to change. They could see the moon was made of rocks. Most scientists thought moon rocks would be different from those on Earth. This was because they believed the moon had once been a planet that had been caught in the earth’s gravity millions of years earlier.
In 1969 moon rocks were finally brought to the earth and studied. Much to their surprise, scientists found that, except for water, the moon and the earth were made of the same things. Once again new ideas were needed for this new information.
After years of study, most scientists now think that the moon was once part of Earth. They believe very early in its history, maybe 4 million years ago, something about the size of Mars hit Earth. This sent billions of rocks into space around our planet. These rocks slowly joined together and after many years became the moon.
In the future, even though our ideas about the moon may change again, we will still be interested in it.
【小题1】From the passage we know the moon was made of_____________.

The earth moves round the sun ,and the moon goes round the earth .When our part（部分）of the earth turns to the sun ,it is day ,When our part of the earth turns away from the sun ,it is night. The sun is much bigger than the moon .But sometimes the moon looks bigger than the sun, because it's much nearer to the earth. The sun is very bright .It gives a very strong light .The moon looks quite bright, too .But it doesn't give any light at all. The moon looks much bigger and brighter than the stars .But actually（事实上）, the stars are much bigger and brighter than the moon .They look smaller than the moon because they're much farther away from us.

1.Sometimes the moon looks bigger than the sun, because______.

2.The stars ______.

3.When it is day, _______.