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机械设备润滑的主要目的是什么？

答案

参考答案：

在机械零件相互接触的工作表面间加一层有流动性能的材料，以隔离金属与金属之间的直接摩擦，从而降低摩擦阻力和提高设备的使用寿命。

实验题

某科研小组用MnO2和浓盐酸制备Cl2时，利用刚吸收过少量SO2的NaOH溶液对其尾气进行吸收处理。

(1)请完成SO2与过量NaOH溶液反应的化学方程式：

SO2＋2NaOH== ________________________。

(2)反应Cl2＋Na2SO3＋2NaOH===2NaCl＋Na2SO4＋H2O中的还原剂为__________。

(3)吸收尾气一段时间后，吸收液(强碱性)中肯定存在Cl－、OH－和SO42－。

请设计实验，探究该吸收液中可能存在的其他阴离子(不考虑空气中CO2的影响)

①提出合理假设。

假设1：只存在SO32－；

假设2：既不存在SO32－，也不存在ClO－；

假设3：____________。

②设计实验方案，进行实验。请在表格中写出实验步骤以及预期现象和结论。限选实验试剂：3 mol/L H2SO4、1 mol/L NaOH、0.01 mol/L KMnO4、淀粉－KI溶液、紫色石蕊试液。

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填空题

Renowned U. S. economist, John Rutledge, who helped frame the fiscal policies of two former U. S. presidents, warned that an abrupt rise in China’ s currency could lead to another Asian financial crisis. The founder of Rutledge Capital told the media that if the yuan rises (1) it would discourage foreign direct investment in China while (2) by market speculators. Currency change is more difficult for investors and (3) .
The Chinese currency has appreciated by (4) since July 2005 when the country allowed the yuan to (5) within a daily band of 0.3 percent. The analysts are expecting the currency to rise (6) by the end of this year. But if the yuan rose 20 to 30 percent, as some U. S. politicians are demanding, it would (7) causing a recession and deflation. Similar advice to allow an abrupt appreciation of a currency led to (8) in 1997, and came very close to destroying (9) . The U. S. economist says that investors want foremost to (10) associated with large fluctuations in currency and inflation. They (11) after evaluating risks to benefits such as (12) . A rising yuan would drive up labor costs for foreign investors and would not (13) .
Earlier reports said that currency speculators had pumped (14) U.S. dollars into China by the end of last year, with another 70 billion U. S. dollars (15) in the first three months of this year. There is no way to (16) of this type of investment and many economists disagree that (17) is so high. Instead of further appreciating its currency, China should make the yuan (18) . If the yuan were more easily converted into foreign currencies it would allow Chinese companies to expand overseas, (19) , and provide management experience and capital that China needs. It would also (20) and reduce speculative money coming into the country.

Renowned U. S. economist, John Rutledge, who helped frame the fiscal policies of two former U. S. presidents, warned that an abrupt rise in China’ s currency could lead to another Asian financial crisis. The founder of Rutledge Capital told the media that if the yuan rises (1) it would discourage foreign direct investment in China while (2) by market speculators. Currency change is more difficult for investors and (3) .
The Chinese currency has appreciated by (4) since July 2005 when the country allowed the yuan to (5) within a daily band of 0.3 percent. The analysts are expecting the currency to rise (6) by the end of this year. But if the yuan rose 20 to 30 percent, as some U. S. politicians are demanding, it would (7) causing a recession and deflation. Similar advice to allow an abrupt appreciation of a currency led to (8) in 1997, and came very close to destroying (9) . The U. S. economist says that investors want foremost to (10) associated with large fluctuations in currency and inflation. They (11) after evaluating risks to benefits such as (12) . A rising yuan would drive up labor costs for foreign investors and would not (13) .
Earlier reports said that currency speculators had pumped (14) U.S. dollars into China by the end of last year, with another 70 billion U. S. dollars (15) in the first three months of this year. There is no way to (16) of this type of investment and many economists disagree that (17) is so high. Instead of further appreciating its currency, China should make the yuan (18) . If the yuan were more easily converted into foreign currencies it would allow Chinese companies to expand overseas, (19) , and provide management experience and capital that China needs. It would also (20) and reduce speculative money coming into the country.
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