表面式换热器中，冷流体和热流体相反方向平行流动，称此换热器为（）。
A、混合式换热器
B、逆流式换热器
C、顺流式换热器
参考答案：B
膀胱冲洗过程中注意观察（）、（）。
The lawyer was so kind that he devoted all his spare time he had _____ the disabled. [ ]
A. to helping
B. helped
C. helping
D. to help
