问题 问答题

简述气相色谱法测定三卤甲烷的原理。

答案

参考答案:三卤甲烷主要是指自来水中的CHCl3,CHBrCl2,CHBr2Cl和CHBr3。将水样置于有一定液上空间的密闭容器中,水中的挥发性组分就会向容器的液上空间挥发,产生蒸气压。在一定条件下,组分在气液两相达到力学动态平衡(组分分压服从拉乌尔定律)。取气相样品用带有电子捕获检测器的气相色谱仪进行分析,外标法定量,可以得出组分在水样中的含量。

改错题

第二卷(共35分)

第四部分:写(共两节,满分35分)

第一节:短文改错(共10小题;每小题1分,满分10分)

此题要求改正所给短文中的错误。对标有题号的每一行做出判断:如无错误,在该行右边横线上划一个勾(√)如有错误(每行最多只有一个错误),则按下列情况改正:

此行多一个词:把多余的词用斜线(\)划掉,在该行右边横线上写出该词,并也用斜线划掉。

此行缺一个词:在缺词处加一个漏字符号(∧),在该行右边横线上写出该加的词。

此行错一个词:在错的词下划一横线,在该行右边横线上写出改正后的词。

注意:原行没有错的不要改。

Considering how much time every day a student spends     

read books, newspapers, letters and notices, you’ll know    76.          

what a important learning skill reading is. One can get      77.          

succeed and enjoyment throughout his life. Eighty-five      78.          

per cent of university work, for example, need reading.      79.          

Reading is the understand of words and the connection       80.          

between them, so never read some related words separate. Before      81.          

reading, it is necessary to decide what you read is worth    82.         

reading or not. While reading, it’s necessary to decide what is worth        83.         

taking notice of. Try to grasp the main idea of what you are reading it.     84.          

A good student will always try to find out his weakness so as improve      85.          

his reading habits and his reading skills.

填空题