除去下列物质中的杂质（括号内为杂质），所选试剂及操作方法均正_爱下问搜题

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问题选择题

除去下列物质中的杂质（括号内为杂质），所选试剂及操作方法均正确的一组是

A．待提纯的物质：碳酸钙（泥沙）；选用的试剂：水；操作的方法：溶解、过滤、结晶

B．待提纯的物质：Cu（CuO）；选用的试剂：稀盐酸；操作的方法：溶解、过滤、洗涤、干燥

C．待提纯的物质：CuSO₄（H₂SO₄）；选用的试剂：氢氧化钠溶液；操作的方法：过滤

D．待提纯的物质：CO₂（CO）；选用的试剂：氧气；操作的方法：点燃

答案

答案：B

题目分析：根据原物质和杂质的性质选择适当的除杂剂和分离方法，所谓除杂（提纯），是指除去杂质，同时被提纯物质不得改变。除杂质题至少要满足两个条件：①加入的试剂只能与杂质反应，不能与原物质反应；②反应后不能引入新的杂质。A、碳酸钙、泥沙均难溶于水，不能采取加水溶解、过滤、结晶的方法进行分离除杂，故选项所采取的方法错误；B、CuO能与稀盐酸反应生成氯化铜和水，铜不与稀盐酸反应，能除去杂质且没有引入新的杂质，符合除杂原则，故选项所选试剂及操作方法均正确；C、H₂SO₄和CuSO₄均能与NaOH溶液反应，不但能把杂质除去，也会把原物质除去，不符合除杂原则；故选项所采取的方法错误；D、除去二氧化碳中的一氧化碳不能够通氧气点燃，这是因为当二氧化碳（不能燃烧、不能支持燃烧）大量存在时，少量的一氧化碳是不会燃烧的；且除去气体中的气体杂质不能使用气体，否则会引入新的气体杂质，故选项所采取的方法错误，故选B。

完形填空

阅读下面短文，补全表格中所缺的信息。
How important is music? When they are asked this question, students and parents usually answer that music is nice, but not very important. It is often considered only as fun, but not the first choice for education. This opinion is shortsighted(短视的). In fact, music education is necessary and important for all students.
Music tells us who we are. Music shows people’s thinking and values, as well as the social environment it came from. just as Mozart music is a lifestyle, rock music is also a lifestyle.
Music provides a kind of ability to know the world in a different way. Science explains how the sun rises and sets. Music studies the emotive(情感的) meanings. We need every possible way to discover and respond(回应) to our world because no one way can get it all.
Music is a form of thought, as powerful as science. It is a way we human beings “talk” to each other. Through the language we express our feelings, our discoveries, our ideas and our hopes so that they can be shared with others. When we do not let our children receive good music education, we take away from them the meanings that music expresses. Science does not tell us what it means to be human. Music does.
So music education is much more necessary than people generally realize.

小题1:__________________________ is of great importance
Introduction	Shortsighted opinion: Music is only a way of fun, not the top choice for education. Truth: music education is important for all students.
Main Body	A way to tell who we are	Music not only shows the social environment it came form but also expresses people’s 小题2: _____________________.
	A way to know the world	We need discover and respond to our world because 小题3: ___________.
		Science explains how nature goes.	Music studies the 小题4:_________ of man and nature.
	A way to communicate with each other	We use music to share our feelings, discoveries, ideas and hopes with others.
		Music, different from 小题5:_________________, tells us what it means to be human.
Conclusion	Music education is necessary.

单项选择题

根据城市进化理论，城市发展的“相对分散”阶段主要出现于( )。

A．工业化初期

B．工业化成熟期

C．后工业化初期

D．后工业化成熟期