1. 阅读理解

All living things on the earth depend on the sun. Without the sun all living things on the earth will die.

The sun is a star. In space there are thousands of stars like the sun. They are almost as large as it and as hot as it. At night you can see many stars, but in the daytime you can only see one star--the sun.

The sun is much nearer to us than any other stars. That is why it looks like the biggest and brightest of all the stars. The distance(距离) of the sun from the earth is as much as 150 million kilometres. Most of the stars are thousands of light years away from the earth.

Do you know what a light year is? Light travels about300, 000 kilometres a second(秒). One light year is how far light travels in one year.

1. （1） From the passage, we know in space the sun is a ________.

   A . star B . solar system C . planet D . moon
3. （2） The sun looks like the biggest of all the stars because the other stars ________.

   A . are too small B . are too far away from the earth C . are too heavy D . are moving around the solar system
5. （3） Scientists often use ________ to measure(测量)the distance in the universe.

   A . light year B . kilometre C . millions of kilometres D . thousands of miles