I have no ________ that he will pass the exam，but I still think there is something about whether he has

really got everything ready.[ ]

A．doubt  

B．wonder  

C．chance  

D．point

如图所示，L₁和L₂是两只相同的小灯泡，a、b是电流表或电压表。闭合开关S后，若两灯都能发光，则

A．a、b均是电流表

B．a、b均是电压表

C．a为电流表，b为电压表

D．a为电压表，b为电流表