影响精馏塔正常采出的因素有()。
A.LV634阀故障
B.冷却器失去作用
C.F620罐压高于塔压
D.F690罐压高于塔压
参考答案:A, B, C, D
Tom could swim very well at the age of seven. [ ]
A. at he age of seven
B. at his age of seven
C. when she was seven
D. when he was seven
一般而言,头皮裂伤清创缝合的时限允许放宽至()
A.18小时
B.24小时
C.12小时
D.8小时
E.6小时