A:它们的线速度之比为v1∶v2 =∶1
B:它们的运动周期之比为T1∶T2 = 1∶
C:它们的向心加速度之比为a1∶a2 = 4∶1
D:它们的向心力之比为F1∶F2 = 4∶1
How color at new red
A: Look ____ my ____ skirt.
B: ____ nice!
A: What ____ is my skirt?
B: It's ____.
A: Red? It's yellow. (黄色的)
—______you tell me the differences between these two photos?
—No. They look quite similar, nearly the same.