三相半波可控整流电路在换相时,换相重叠角γ的大小与哪几个参数有关 ( ) 。A、α、Id、 XL、U2φ;B、α、Id;C、α、U2;D、α、U2、 XL;
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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