哪种属于间断控制器（）。
A.推拉开关
B.手柄
C.旋纽
D.选择旋钮
参考答案：D
It was _______ he does _______ makes his students enthusiastic about school. (原创)
A．that; that
B．what; what
C．that; what
D．what; that
物理学家用______来形象地描述空间磁场情况，在磁体外部这些线都是从磁体的______极出来，回到磁体的______极．
