绚丽____ ____颜____色 ____扑鼻
利用三颗位置适当的地球同步卫星，可使地球赤道上任意两点之间保持无线电通讯，目前地球同步卫星的轨道半径为地球半径的6.6倍，假设地球的自转周期变小，若仍仅用三颗同步卫星来实现上述目的，则地球自转周期的最小值约为（ ）
I am Bill Jones. I am a teacher of English. My wife is Linda Jones. She is a nurse. We have a daughter and a son. We have many friends.Look! These are my friends. This is Mr. Black. He is a worker. He works in a shoe factory He makes shoes there. That’s Mrs. Black. She is a worker on a farm near here. The girl is their daughter. She is a student. She is thirteen. The boy is their son. He is a young soldier（战士）. His name is Carl Black.
比较大小：25 ____5．
