【单选题】【消耗次数:1】
换向器在直流电动机中是起什么作用?
整流作用
逆变作用
两者都是
都不是
参考答案:
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相关题目
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②  错误
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随机题目
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【单选题】 This year’s total output value of industry and agriculture will increase ____ 5 percent over last year.
①  to
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①  be fixed
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①  weren’t
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【单选题】 At that time, the committee, so far as I know, _______ of three scientists, two professors, and four senior engineers.
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