（）是火电厂的理论循环，是组成蒸汽动力的基本循环。
A.卡诺循环
B.朗肯循环
C.再热循环
D.回热循环
参考答案：A
12×400口算时想______和______相乘得______，积是______．
He ___________ unwisely, but he was at least trying to do something helpful.
A．may have acted
B．must have acted
C．should have acted
D．would act
