Do you remember ________ when the car accident happened?
A:what you were doing
B:what were you doing
C:what you did
D:what did you do
一株苹果树的不同枝条分别结出红富士和国光两种果实,所采用的繁殖方式为( )
如图所示,重力为G的均匀木棒竖直悬于O点,在其下端施一始终垂直于棒的拉力F,让棒缓慢转到图中虚线所示位置,在转动的过程中( )
0.4×0.8×125×25=____