题目内容

交流变压变频调速(VVVF)拖动电梯的调速原理是通过调节交流电机定子供电的幅值和频率而实现电动机的转速变化。

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Whenever he appeared on the stage, the famous actor was greeted with a () of applause from the audience.

A.piece
B.collection
C.number
D.burst

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A.on the condition
B.on terms
C.under the condition
D.in terms

股票的发行价格有()。

A. 面额发行
B. 折价发行
C. 溢价发行
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We met him in the Grand Hotel ().

A.another day
B.the other day
C.some other day
D.the some day

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