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问题 单项选择题

水中有机氯农药测定方法有比色法、薄层法和气相色谱法等，其中灵敏度最高，且被广泛应用的方法是（）

A.比色法

B.薄层法

C.气相色谱法-氢火焰离子化检测器

D.气相色谱法-电子捕获检测器

E.气相色谱法-火焰光度检测器

答案

参考答案：D

解析：一般水中有机氯农药含量很低，通常用气相色谱-电子捕获法测定。采用的富集方法是环己烷或石油醚萃取，但有时溶剂峰变宽，干扰六六六出峰，需重蒸馏至无干扰峰出现。

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单项选择题

Previous studies have indicated that eating chocolate increases the likelihood of getting heart disease. However, a new, more reliable study has indicated that eating chocolate does not increase the likelihood of getting heart disease. When the results of the new study become known, consumption of chocolate will undoubtedly increase.
Which of the following is an assumption on which the conclusion above is based

A．Most people who eat a great deal of chocolate will not get heart disease.

B．Although they believe that eating chocolate increases the likelihood of getting heart disease, some people still eat as much chocolate as they want.

C．People who have heard that eating chocolate increases the likelihood of getting heart disease do not believe it.

D．There are people who currently eat as much chocolate as they want because they have not heard that eating chocolate increases the likelihood of getting heart disease.

E．(E) There are people who currently limit their consumption of chocolate only because they believe that eating chocolate increases the likelihood of getting heart disease.
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