题目内容

当主驱动链被过度拉伸或断裂,主驱动链保护装置能使自动扶梯(自动人行道)停止运行。

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Can the best student become ()?

A.as best as ever
B.as good as ever
C.better than ever
D.the best as ever

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。

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

Now let us analyze the flight of a spacecraft () of what we have learned about motion and gravity.

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

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