问题 问答题 简答题

为什么要控制系统的PH值?

答案

参考答案:

由于抽提进料中常常带有活性氧,特别是在真空下操作的溶剂回收系统,可能泄漏造成外界氧进入系统而使环丁砜产生SO2等酸性物质,另外因系统再沸器周围发生过热而使环丁砜分解,不断积累对设备腐蚀严重.通过在回流芳烃罐加入单乙醇胺,贫溶剂的PH值控制在5.5-6.0之间,PH值降低意味着溶剂已经发生了氧化降解。

完形填空

阅读下面短文,根据所给语境,按要求完成下列各题。

Many of the expressions using water haven’t enjoyable meanings in English.

“Hot water” was used five hundred years ago to mean being in trouble. One story says it got the meaning from throwing hot water down on enemies (敌人) attacking a town. That happens no longer, but we still get into hot water.

When we are in hot water, we are in trouble. It can be any kind of trouble, serous or not so serious. A person who breaks a rule can be in hot water with the police. A young boy can be in hot water with his mother if he walks in a house with dirty shoes.

“Water over the dam(水坝)” is another expression about a past event. It’s something that finishes and it cannot be changed. The expression comes from the idea - water has run over a dam and it cannot be brought back again. When a friend is troubled by a mistake he has made, you might tell him to forget about it. You can say “It’s water over the dam.”

“Throwing cold water” means “not to like an idea”. For example, you want to buy a new car because the old one has some problems, but your parents throw cold water on the idea, because they think a new car costs too much.

小题1:阅读短文,并把①处的句子翻译成汉语。

___________________________________________________________________________

小题2:阅读短文,完成下面的句子(每空一词)。

When you say “It’s water over the dam.” to your friend, you want to tell him to __________the __________ he has made.

小题3:用文章中关于“water”的英语短语填空,并使句子通顺。

Your friend invites you to go hiking, but you don’t want to. You can _____________________ on the idea.

单项选择题