引起再生塔超压，后果最严重的是（）
A、输送CO2的压缩机突然停机
B、再生塔溶液超温
C、再生塔压控阀失灵而全关
D、富液控制阀失灵而全开
参考答案：D
_____ is your mother? She's forty． [ ]
A. How old
B. How
C. How age
D. What age
His name is on the _______ of my tongue, but I just couldn’t remember it.
A．tip
B．top
C．side
D．end
