单词拼写（每小题1分，共10分）
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 h______as the sun. At night you can see many stars, but in the day you can only see one star------ the sun.
The sun is much n____ to us than any other star. 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______.