弯管的弯曲点分为()
A.起端点
B.起弯点
C.中弯点
D.终弯点
参考答案:B, C, D
She hasn't told me when she ______ her new novel, but she says when she ______ it, I will be the
first reader. [ ]
A. will finish, will finish
B. finishes, finishes
C. will finish, finishes
D. finishes, will finish
如图所示,质量为m,带电量为-q的粒子,从两平行电极板正中央垂直电场线和磁感线以速度v飞入.已知两板间距为d,磁感强度为B,这时粒子恰能直线穿过电场和磁场区域(重力不计).今将磁感强度增大到某值,则粒子将落到极板上.当粒子落到极板上时的动能为______.