问题 选择题

下列说法中,正确的是(  )

A.过量的Fe与Cl2充分反应,生成FeCl2

B.少量CO2通过BaCl2溶液能生成白色沉淀

C.可以用澄清石灰水鉴别苏打和小苏打

D.Na2O2和活性炭均能使品红溶液褪色,但褪色原理不同

答案

A.铁在氯气中燃烧,无论氯气是否过量都只生成氯化铁,故A错误;

B.盐酸的酸性大于碳酸,所以二氧化碳和氯化钡溶液不反应,故B错误;

C.Na2CO3+Ca(OH)2═CaCO3↓+2NaOH、2NaHCO3+Ca(OH)2═CaCO3↓+Na2CO3+2H2O,都出现白色沉淀,无法鉴别,故C错误;

D.过氧化钠具有强氧化性,活性炭具有吸附性,过氧化钠使品红褪色是利用过氧化钠的强氧化性,活性炭使品红溶液褪色是利用活性炭的吸附性,所以褪色原理不同,故D正确;

故选D.

选择题
写作题

Apple has entered the textbook market. The tech giant introduced iBooks textbooks a couple of weeks ago when it announced its iBooks 2 platform.  They are digital books in a variety of subjects from astronomy to zoology taking in science, maths, history and geography. Apple developed its iPad-based textbooks in connection with major textbook publishers. The company offers a collection of textbooks for high school students.

It sounds like good news for pupils and students. Think of it. No more carrying heavy backpacks full of textbooks. Every textbook you require can be stored on your iPad. Of course there’s a catch. You need to own an iPad and as you know, it is not cheap. You also need to buy digital textbooks, mostly priced each at $14.99 (94.74 yuan) or less. Textbook publishing was worth $8.7 billion in the US alone last year. Will digital books take over completely in education? Is learning going to evolve into something we do on an electronic tablet computer? That remains to be seen.

1.以约30个词概括上文的主要内容。

2.以约120个词就“电子教科书能否代替传统教科书”的话题谈谈你的想法,内容包括:

(1)比较电子教科书和传统教科书各自的优势;

(2)你认为将来电子教科书能否代替传统教科书呢?为什么?

1.作文中可以使用亲身经历或虚构的故事,也可以参照阅读材料的内容,但不得直接引用原文中的句子。

2.作文中不能出现真实姓名和学校名称。

概括准确,语言规范,内容合适,语篇连贯。