You won't want to visit any other mountain if you have seen Wu yue, but you won't wish to see even Wu yue _______returning from Mount Huangshan.
A:about
B:before
C:since
D:after
对平抛运动的物体,已知下列哪个物理量就可确定其初速度( )
如图所示的几种器件,工作时应用了电磁感应现象的是( )