交流电机绕组采用______________措施来削弱谐波电动势。(短距和分布))46三相异步电动机拖动恒转矩负载进行变频调速时,为了保证过载能力和主磁通不变,则U1应随f1按__________规律调节
You can _____ some bottles of wine, or some chocolates, or a bunch of flowers.
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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