问题
选择题
下列现象能说明纸的燃烧是化学变化的是（ ）
A．发光
B．放热
C．变黑
D．产生纸灰
答案
判断纸的燃烧是化学变化需抓住其本质特征产生新物质，发光、放热、变黑都不能说明产生了新物质；产生纸灰说明有新物质生成，是判断发生化学变化的依据．
故选D．
搜题请搜索小程序“爱下问搜题”
下列现象能说明纸的燃烧是化学变化的是（ ）
A．发光
B．放热
C．变黑
D．产生纸灰
判断纸的燃烧是化学变化需抓住其本质特征产生新物质，发光、放热、变黑都不能说明产生了新物质；产生纸灰说明有新物质生成，是判断发生化学变化的依据．
故选D．
阅读下面短文，掌握其大意，然后从各题所给的A、B、C和D项中，选出最佳选项，并在答题卡上将该项涂黑。 In the future, schools will teach at least one thing we do not teach today: the art of self-discovery. There is nothing more___1__in education. We turn out students from our universities who know how to give answers, but not how to___2__questions. Our students do not really get into the centres of wisdom in our culture. They__3___ universities with skills for the workplace, but with no knowledge of how to live, or what___4__is for. They are not taught how to see. They are not taught how to listen. They are not taught the great___5__of obedience（遵守、服从）. They are not taught the true art of___6__. True reading is not just passing our__7___overwords on a page, or__8___information, or even understanding what is being read. True reading is a__9___act. It means seeing first, and then using the__10___. Higher reading ought to be a new subject. As we read, we should try to get something new. I meet people in all__11___of life, and most known in the fields of literature and science, who, though professionals, do not___12__read what is in front of them. They only read what is__13___known to them. I suspect this is happening now, even as you read this__14___. All our innovations(革新), our discoveries, our__15___come from one source: being able first to see what is there, and what is not; to hear what is said, and what is not; but also to think clearly.
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