其它条件相同的情况下，对热交换器而言，冷热流体逆流比并流更能提高传热效率。
参考答案：对
Her parents always ____ her as the cleverest of their children. [ ]
A. regard
B. make
C. keep
D. watch
液一液萃取从机理上分析可分为（）和（）两类
