U型管换热器壳程可以走（）的流体。
A.不易结垢
B.易结垢
C.流速高
D.压力高
参考答案：B
-Why are you in such a hurry, Meimei?
-The fashion clothes are sold in the supermarket at the moment?
A．bought
B．have sale
C．on sale
D．selling
一条正脊四条斜脊，四个斜坡，屋顶面有弧度。这种形式的屋顶叫做()。
