缺词填空
There is nothing more i     to life than the sun. W    the sun, all living things on the earth would die. The sun is a star. In the sky there are t   of stars like the sun. They are as large as the sun and as hot as the sun. At night you can see many stars, but in the daytime you can o   see one star—the sun.
The sun is much n   to us than the other stars. That is w    it looks the biggest and brightest of all the stars. The distance (距离) of the sun from the earth is as m     as 150,000,000 kilometers. Most stars are thousands of light-years a   from the earth.
Do you know what a light-year is? N    in the world travels faster than light. It travels 300,000 kilometers per second. And one light-year is the distance that light can travel in one y   .