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问题 填空题

A、B、C、D、E各物质的转化关系如图所示．

（1）当A为空气中含量最高的单质气体时，A是______（写化学式）．

写出下列反应的化学方程式，并回答有关问题：

①E→C：______；

②实验室制备B：______．能不能用浓硫酸做B的干燥剂？______（填“能”或“不能”）．

（2）当A为淡黄色固体单质时，A是______（写化学式）．写出下列反应的化学方程式：

①C→D：______；

②E与木炭反应：______．

答案

（1）当A为空气中含量最高的单质气体时，应为N2，则C为NO，B为NH3，D为NO2，E为HNO3，故答案为：N2；

①E→C的反应为稀硝酸与Cu的反应，反应的方程式为3Cu+8HNO3（稀）=3Cu（NO3）2+2NO↑+4H2O，故答案为：3Cu+8HNO3（稀）=3Cu（NO3）2+2NO↑+4H2O；

②实验室应氯化铵与氢氧化钙在加热条件下反应制备氨气，反应的化学方程式为2NH4Cl+Ca（OH）2

△
.
CaCl2+2NH3↑+2H2O，氨气是碱性气体，不能与浓硫酸做干燥剂，

故答案为：2NH4Cl+Ca（OH）2

△
.
CaCl2+2NH3↑+2H2O；不能；

（2）当A为淡黄色固体单质时，A是S，B是H2S，C是SO2，D是SO3，E是H2SO4，故答案为：S；

①C→D的反应为SO2在催化剂条件下反应生成SO3，反应的方程式为2SO2+O2

催化剂
△
2SO3，故答案为：2SO2+O2
催化剂
△
2SO3；

②浓硫酸在加热条件下与碳发生氧化还原反应，方程式为C+2H2SO4 （浓）

△
.
CO2↑+2SO2↑+2H2O，故答案为：C+2H2SO4 （浓）
△
.
CO2↑+2SO2↑+2H2O．

填空题

Large companies need a way to reach the savings of the public at large. The same problem, on a smaller scale, faces practically every company trying to develop new products and create new jobs. There can be little hope of raising the money needed from friends and people we know, and while banks may agree to provide short-term finance, they are generally unwilling to provide money, for long-term projects. So companies turn to the public’ inviting people to lend them money, or take a share in the business in exchange for a share in future interests. This they do by issuing stocks and shares in the business through the Stock Exchange. By doing so they can put into circulation the savings of single persons and institutions, both at home and abroad.
When the saver needs his money back, he does not have to go to the company with whom he originally placed it. Instead he sells his shares through a stockbroker to some other Saver who is seeking to invest his money.
Many of the services needed both by industry and by each of us are provided by the government or by local organizations. Without hospitals, roads, electricity, telephones and railways, this country could not work. All these require continuous spending on new equipment and new development if they are to serve us properly, requiring more money than’ it is raised through taxes alone. The government, local organizations and nationalized industries therefore frequently need to borrow money to finance: major capital spending, and they, too, come to the Stock Exchange.
There is hardly a man or woman in this country whose standard of living does not depend on the ability of his or her employers to raise money to finance new development. In one way or another his new money must come from the savings of the country; The Stock Exchange exists to provide a channel through which these savings, can reach those who need finance.

The money which enables these companies to go ahead with their projects is ______.
A. exchanged for part ownership in the Stock Exchange
B. raised by the selling of shares in the companies
C. repaid to its original owners as soon as possible
D. invested in different companies in the Stock Exchange
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问答题 简答题

试述慢性肾衰竭的超声表现。
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