题目

人造地球卫星的轨道半径越大，则A．线速度越小，周期越大B．角速度越小，周期越大C．线速度越大，周期越小D．加速度越大，周期越大 答案：AB— What do you think made Mary so excited? — the annular solar eclipse(日环食).A.As she watchedB.WatchedC.WatchingD.Because of watching