The professor thought that the idea the young engineer________was worth considering.
A:brought up
B:made up
C:set up
D:picked up
下列列举的物体中,与乒乓球的形状类似的是( )
如图所示,用手竖直捏住物理课本,手和课本都在空中静止。下列各对力中属于平衡力的是( )