两颗人造卫星绕地球做匀速圆周运动,它们的质量之比为mA:mB=1:2,轨道半径之比rA:rB=3:1,则下列说法正确的是( )
A:它们的线速度之比为vA:vB=1: 3
B:它们的向心加速度之比为aA:aB=1:9
C:它们的向心力之比为FA:FB=1:18
D:它们的周期之比为TA:TB=3:1
下列划线字解释全都正确的一项是 ( )
— Do you think I should wear an orange shirt today?
— Yes. orange can bring you good luck, it is good for your interview.