题干

下列有关实验操作、现象、解释或结论都正确的一组是(   )

选项

实验操作

现象

解释或结论

A

将水加入浓硫酸中配置成稀硫酸,将镁条置于其中

有气泡产生

Mg是活泼金属

B

验纯后,将纯净氢气直接在空气中点燃

产生淡蓝色火焰

氢气可以在空气中安静的燃烧

C

向一未知无色溶液中,加入适量的稀盐酸溶液

有无色气体产生

该无色未知溶液中一定有CO32

D

将ag的铁钉投入到硫酸铜溶液中,反应一段时间后,取出、洗净、烘干、称量为bg

铁钉上覆盖一层红色的物质

金属活动顺序为:Fe>Cu,且析出铜的质量为(b﹣a)g

A:A  

B:B  

C:C  

D:D

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答案(点此获取答案解析)

B

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    You have probably been told by your high school instructor that writing is an important and practical skill. However, you may not be convinced that the ability to write will be important in your own future. If so, you will be surprised at the results of a recent survey by the National Institute of Education. More than four thousand working men and women who had graduated fifteen years earlier were asked to name the courses they would have taken in college if they had known better. The designer of the survey expected people to name courses in computer science, mathematics, or business. But the course most often mentioned was writing.

    If you already have a job, you are probably not surprised at their answers. Many jobs require the ability to write. Despite the increasing use of the telephone and the computer, much information must be communicated in writing.Some ten million people—managers, engineers, sales representatives, and many others— write regularly as part of their jobs. Summaries, reports, reports, letters and speeches are required in today's work world. The ability to write, therefore, is an important skill. The successful individual is almost always the one who can communicate successfully in writing.

    Writing communicates your thoughts and feelings to others; it also tells you something about yourself. Maybe this is what Eldridge Cleaver had in mind in his autobiography, “I started to write... to save myself...I had to seek out the truth... I had to find out who I am and what I want to be ,what type of man I should be ,and what I could do to become the best of which I was capable.”