It is high time that theboy (eat) less sugar
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The old lady always wishes that she (be) in her twenties
If he were reelected four years ago, he (take) actions then.
正弦电流通过R和C两个元件时，若UR=30V，UC=40V，则总电压U=UR+ UC =70V。
A. 对
B. 错
在正弦交流电路中，电源的频率越高，则电感的感抗越大、电容的容抗越小。
A. 对
B. 错
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