水银气压表读数须经仪器差、重力差和温度差三步订正方是本站气压。（）
参考答案：对
产后三急是指（）
A.泄泻
B.盗汗
C.呕吐
D.自汗
E.腹痛
—Why aren’t they here yet?
—They the bus.
A．can have missed
B．must be late for
C．may have missed
D．might be late for
