通常把工业废水分成（）大类。
A.两
B.三
C.四
D.五
参考答案：A
Having cycled for two days, Howard at last arrived at ______ was a place famous for its beautiful scenery.
A．where
B．that
C．which
D．what
防雷监督板工作电源范围是（）。
A.4.5～5.5V
B.11～13V
C.30～34V
D.220V左右
