Man has invented four kinds of satellites. The first kind of satellites studies the1of the earth. They are used to make maps. They also help countries to see where they can2oil or gold.

    The second kind of satellites is used to3ships and planes. A ship or a plane can send a message to the satellite and can find out4it is.

    The third kind of satellites studies the weather. These satellites5clouds and strong winds moving across the earth. They warn countries to make preparations when very6weather is coming. They7of the earth from thousands of miles above it and send the photos to weather stations on the ground.

    8kind is used for communication. Telephone calls9countries can be sent by these satellites. Some can carry hundreds of calls at one time. The call is sent to the satellite then the10sends it to a station in the country and this country is being phoned. These satellites also carry pictures; they can receive and send about eight programs at a time.

    You might see aliens in books and movies. They look strange. They are very smart. They travel in spaceships.

    But are there really aliens in space? British scientist Stephen Hawking, 68, thinks so. He says that people should not look for aliens. He thinks they are dangerous. On a new British TV program, Hawking says, "It is quite possible that there are aliens in space. They might live in big spaceships. They have used up all the resources（资源）from their home planet. "He thinks such aliens are sure to get resources from Earth and then go away. They may bring troubles to Earth, too.

—She             Guangzhou.

    The Earth is a planet. It and seven other planets go  the Sun. We  (call)the eight planets and the Sun the solar system.  first planet, next to the Sun, is Mercury(水星). It is 58 million  (kilometer)from the Sun. Venus(金星)is the second planet from the Sun, and  (we)planet, the Earth, is the third. It is 150 million kilometers from the Sun.

    Jupiter(木星), Saturn(土星), Neptune(海王星)and Uranus(天王星)are all  (big)than the Earth,   Venus, Mars and Mercury are smaller than the Earth.

    Animals, trees and humans can only live  the Earth-the other planets in our solar system do not have air  water. Do any planets in other solar systems have  (life)? We don't know about it.

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