腹泻，大便呈米泔样常见于（）
A.急性肠炎
B.霍乱
C.直肠癌
D.伤寒
E.过敏性肠炎
参考答案：B
—Why didn't you answer my phone when I phoned you at about 11 p. m. yesterday?
—I ___________and failed to hear the phone.
A．might have slept
B．must be sleeping
C．might be sleeping
D．must have been sleeping
采用氯氧化二价铁时，每氧化5mg/L的二价铁，理论上需投加( )的氯。
A．3.2mg/L B．1.6mg/L C．6.4mg/L D．3.5mg/L
