―Why are you so sweaty?I football with my classmates and how I want to have a drink!A.was playing B.had been playing C.have played D.played 答案:A 设行星绕恒星运动轨道为圆形,则它运动的周期平方与轨道半径的三次方之比T2/R3=K为常数,此常数的大小: ( )
A.只与恒星质量有关
B.与恒星质量和行星质量均有关
C.只与行星质量有关
D.与恒星和行星的速度有关