城市污水处理工艺中，必须设置格栅的是( )处理。
A．一级B．二级C．三级D．多级
参考答案：A
But for the storm, we __________ a pleasant journey, but had to turn back halfway．
A．would have
B．would have had
C．will have
D．had
什么是遮阳系数Sc，它反映的是哪一部分传热？
