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问题 单项选择题

在自动准同步并车中，所检测的脉动电压的周期短，说明（）。

A.待并发电机与电网的频率差小

B.待并发电机与电网的频率差大

C.待并发电机与电网的电压差小

D.待并发电机与电网的电压差大

答案

参考答案：B

填空题

用所给词的适当形式填空。

1. He thought about going to Greece or Canada, but finally _____ (decide)on China.

2. My uncle is _____ (leave) for Shanghai next Sunday.

3. Isabella finished _____ (make)her last movie last week.

4. He had a very _____ (relax) vacation.He was very _____ (relax)
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选择题

Koalas come from __________. They are very cute.

A．Africa

B．China

C．Japan

D．Australia
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