求高人幫我解決1篇英語首字母填空
.Since t_ of millions of years the moonhas been to going around Earth.A__ that time the moon was the only satellites of E__.Today the earth has many other satellites(衛(wèi)星）.All of them are made by man.These man-made satellites are m_ smaller than the moon .Some of them will still go round the earth thousands of years .
Man-made satellites don't f__ because they are going too fast to do s__.The pull of the earth k__ them from doing this .As a result,they travel in an orbit（軌道） round the earth .
If a man-made satellite travels about a certain height,it can keep g__ round the atmosphere,and there is n__ to slow it down .If it travels lower than that ,it will be s__ down so much that it will fall to the earth.