____teacher of my grandmother’s is coming the day after tomorrow. I’m wondering

how old____woman she should be.

A．The; a

B．A; a

C．A; the

D．The; the

乙二醇精制塔做真空试验时，下列说法不正确的是（）。

A、塔的压力不是定值

B、塔是负压

C、真空泵正常运行

D、联塔阀关闭