[单选题]

20/5t桥式起重机电动机转子回路测试时,在断电情况下扳动手柄,当转动5个挡位时,要求R5、R4、R3、R2、R1各点依次与()点短接。

A .R6

B .R7

C .R8

D .R9

参考答案与解析: