If the temperature of the liquid is lower than the saturation temperature for the existing pressure, it is called a _______ liquid.
A. superheated
B. subcooled
C. saturation
D. dry saturated
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If the efficiency of a real engine is significantly _______ the efficiency of a Carnot engine between the same limits, then additional improvements may be possible.
A. lower than
B. more than
C. equal to
D. greater than
已知某用电设备的阻抗为|Z|=10Ω,R=3Ω,则其功率因数cosφ =______ 。
在三相交流电路中,保险丝不可以安装在中性线上。( )
三相异步电动机的调速方法中,变频调速可实现无级变速( )