题干

以下说法正确的是(  )

①工业上采用液化空气的方法制备氧气和氮气

②氢气、甲烷在点燃前要检验气体的纯度

③铝是人类最早利用的金属材料

④氢氧化钠固体潮解、变质与水蒸气和二氧化碳有关

⑤干冰灭火既能降温,又能隔绝空气,而且灭火后不会留痕迹

⑥二氧化硫、氮氧化物、一氧化碳和二氧化碳都是大气污染物.


A:②③⑤⑥  

B:①②④⑥ 

C:①②④⑤

D:①③④⑤

上一题 下一题 0.0难度 选择题 更新时间:2019-09-19 09:43:55

答案(点此获取答案解析)

C

同类题4

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。

    Maybe you are an ordinary student. ____ This is not necessarily so. Anyone can become a better student if he or she wants to. Here's how:

    Plan your time carefully. When planning your work, you should make a list of things that you have to do. After making this list, you should make a schedule of your time. First arrange your time for eating, sleeping, dressing, etc, then decide a good, regular time for studying. ____ A weekly schedule may not solve all your problems, but it will force you realize what is happening to your time.

    Make good use of your time in class. ____ Listening carefully in class means less work later. Taking notes will help you remember what the teacher says.

    Study regularly. When you get home from school, go over your notes, review the important points that your teacher is going to discuss the next day, read that material. ____ If you do these things regularly, the material will become more meaningful, and you will remember it longer.

    Develop a good attitude towards tests. The purpose of a test is to show what you have learned about a subject. The world won't end if you don't pass a test, so don't be over worried.

    ____ You will probably discover many others after you have tried these.

A. This will help you understand the next class.

B. You probably think you will never be a top student.

C. Don't forget to set aside enough time for entertainment.

D. No one can become a top student unless he or she works hard.

E. There are other methods that might help you with your study.

F. Take advantage of class time to listen to everything the teacher says.

G. Make full use of spare time to take note of what the teacher says in class.