题型:单项选择题 有乙烯开车时,关于脱乙烷塔系统的预冷,下列说法正确的是()。A.脱乙烷塔不需要预冷B.脱乙烷塔的预冷伴随着泵的预冷同时进行C.预冷在压缩三机运转正常后才能进行D.预冷只要气相预冷即可 查看答案
题型:选择题 — Do you ask why I am learning English?— Yes, I mean, what are you going to do with it? Are you going to be a teacher of English or something like ?[ ]A. itB. himC. thatD. such 查看答案