A．( We decided to purchase a camera for our online course

B．( I know that we cannot beat the price for the camera on the Net

C．( The order is that we need to buy the camera cheaper on the Internet

D．( The camera we bought is more expensive than I expected

检查鼠笼式电动机笼条断裂的方法是（）。

A、电压电流法

B、电压曲线法

C、电流曲线法

D、电桥法