题干

已知反应:N2(g)+3H2(g) 2NH3(g)△H<0,向某体积恒定的密闭容器中按体积比1﹕3充入N2和 H2,在一定条件下发生反应,下图是某物理量(Y)随时间(t)变化示意图,Y可以是(  )

A:N2的转化率

B:混合气体的密度

C:H2的体积百分含量

D:密闭容器内的压强

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答案(点此获取答案解析)

A

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    Every week in China, millions of people will sit in front of their TVs watching teenagers compete for the title Character Hero, which is a Chinese-style spelling bee (拼写大赛). In this challenge, young competitors must write Chinese characters by hand. To prepare for the competition, the competitors usually spend months studying dictionaries.

    Perhaps the show's popularity should not be a surprise. Along with gunpowder and paper, many Chinese people consider the creation of Chinese calligraphy (书法) to be one of their primary contributions to civilization. Unfortunately, all over the country, Chinese people are forgetting how to write their own language without computerized help. Software on smart phones and computers allows users to type in the basic sound of the word using the Latin alphabet. The correct character is chosen from a list. The result? It's possible to recognize characters without remembering how to write them.

    But there's still hope for the paint brush. China's Education Ministry wants children to spend more time learning how to write.

    In one Beijing primary school we visited, students practice calligraphy every day inside a specially decorated classroom with traditional Chinese paintings hanging on the walls. Soft music plays as a group of six-year-olds dip brush pens into black ink. They look up at the blackboard often to study their teacher's examples before carefully attempting to reproduce those characters on thin rice paper. “If adults can survive without using handwriting, why bother to teach it now?'' we ask the calligraphy teacher, Shen Bin, “The ability to write characters is part of Chinese tradition and culture,” she reasons. "Students must learn now so they don't forget when they grow up.” says the teacher.