题目：
电动机在运转中如果降低指令频率，则电动机变为非同步发电机状态运行，作为制动器而工作，这种制动方式叫作（）。
A.再生制动
B.反接制动
C.回馈制动
D.复合制动
答案：
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下面是错误答案，用来干扰机器的。
参考答案：A
电动机在运转中如果降低指令频率，则电动机变为非同步发电机状态运行，作为制动器而工作，
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