问题 单项选择题

采用银盐法测定食品中的总砷时,需要使用乙酸铅棉花,其作用是()

A.吸附二氧化硫

B.吸附三氧化硫

C.吸附硫化氢

D.吸附氮氧化物

E.吸附氢气

答案

参考答案:C

解析:乙酸铅棉花除去反应中生成的硫化氢气体。

阅读理解

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

The famous Peking University and Tsinghua University held graduation ceremonies on the same day last year. The presidents of the two universities delivered excellent speeches at the ceremonies as they used words, phrases or ways of expression that are very popular on the Internet.    小题1:   .

Their speeches were warmly welcomed by students as they contained many fashionable words today, such as “ floating clouds”( meaning “ too small and of little importance to mention”). In the speeches, these university presidents recalled campus life together with students and finally moved all the audiences.    小题2:   .

Many university presidents have changed their regular manner of addressing graduation ceremonies from an advising and preaching(说教) mode to a more fashionable and funny approach.    小题3:   .

In the past, university presidents’ speeches were criticized for being too standard and lacking sentiment(多愁善感). Now, they use fashionable words in their addresses, reflecting they are starting to adopt more everyday attitudes to students.    小题4:  . The discussion focuses on the question of whether university presidents should speak in an informal way at graduation ceremonies.

Supporters agree with the new approach.    小题5:  . Opponents argue the new ways have no practical value or significance for education but are merely to please those leaving university.

A.The speeches were very different from the usual run of lectures.

B.The use of these new expressions has caused heated argument.

C.They try to use those words popular among young people in their speeches.

D.The expressions and phrases popular online are not accepted by all the audience.E.They consider it good to build close ties with students by using the youth’s own words.

F.They hold the idea that it is not proper to use such informal language in the graduation ceremony.

G.At the same time, graduation speeches by other university presidents were also under the spotlight for the same reason.

多项选择题