题干

下列有关叙述能说明非金属元素M比N的非金属性强的是(   )

①非金属单质M能从N的化合物中置换出非金属单质N

②M原子比N原子容易得到电子

③单质M跟H2反应容易得多

④气态氰化物水溶液的酸性HmM>HnN

⑤氧化物对应水化物的酸性HmMOx>HnNOy

⑥熔点M>N

⑦M原子在反应中得到的电子数比N原子在反应中得到的电子数少

⑧M单质能与N的氰化物反应生成N单质

⑨M的最高正价比N的最高正价高.

A:②⑤

B:①②③⑧

C:①②③⑤

D:全部

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答案(点此获取答案解析)

B

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   This sense of responsibility for others is basic to all good societies. And also it is basic to what we call “civil(文明的) society”. China is now working on building a civil society and the high schools in Shanghai want students to take part in that through volunteering. They are supposed to do sixty class hours of volunteer work before graduation. This is something new in China, but it is not new in other countries.

In theCanadian province of Ontario, high school students are required to do forty hours of volunteering. In some American states, the volunteering requirement is one hundred hours. These students spend about an hour a week during the school year and summer vacations, helping the poor, the sick and the old. They also teach young children to read and help to clean up the environment. And studies have shown that this volunteering experience influences students a lot after graduation.

   Some of you may be thinking, “Gee, sixty class hours is a lot. How can I find the time?” In fact, if you finish it in three years, you only need to do the work about three class hours a month. And the time is well spent if it helps you realize that “being your brother’s keeper” makes you a better person and makes society a better place for everyone.