硫化氢水溶液在空气中放久了会变浑浊，这是由于与二氧化硫反应变质造成的。
参考答案：错
—How long in America?
—Two years. I came back last month.
A．have you studied
B．do you study
C．would you study
D．did you study
给水管道安装后，进行水压试验，试验压力不应小于0.4MPa.
