()不是二氧化碳吸收系统发泡时的现象。
A、接触塔压差上升
B、再生塔液位上升
C、碳酸盐溶液闪蒸罐液位下降
D、接触塔分离罐液位上升
参考答案:B
设集合U={1,2,3,4,5},A={1,2,3},B={2,4},则A∩(CUB)=[ ]
A.{1,3}
B.{2,4}
C.{1,2,3,5}
D.{2,5}
There _____ a lot of coal mines in the south, but many of them have been closed or are _____ be closed.
A.use to having; about to
B.used to be; to
C.use to having; going to
D.used to be; supposed to