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问题 问答题

请各写出一个化学反应方程式．

（1）铁在氧气中燃烧：______．

（2）用稀硫酸来清洗铁锈：______．

（3）近日，美国悬赏征集以月球岩石中的含氧物质（如二氧化硅、氧化铝等）为原料在月球上制取氧气的研究成果．请大胆设想，写出一个可能完成此任务的化学方程式：______．

答案

（1）铁在氧气中燃烧生成四氧化三铁，反应的化学方程式为：3Fe+2O2

 点燃 
.
 
Fe3O4．

（2）铁锈的主要成分是氧化铁，与硫酸反应生成硫酸铁和水，反应的化学方程式是为：Fe2O3+3H2SO4═Fe2（SO4）3+3H2O．

（3）氧气可以利用含氧化合物分解获得，如高锰酸钾分解、过氧化氢分解、水分解等，可进行大胆地推测二氧化硅、氧化铝等含氧化合物在一定条件下分解而得到氧气．反应的化学方程式为：SiO2

 一定条件 
.
 
Si+O2↑或2A12O3
 一定条件 
.
 
4Al+3O2↑．

故答案为：（1）3Fe+2O2

 点燃 
.
 
Fe3O4；（2）Fe2O3+3H2SO4═Fe2（SO4）3+3H2O；（3）SiO2
 一定条件 
.
 
Si+O2↑．

单项选择题

老年抑郁症的常见负性生活事件是

A．久病

B．家庭不和

C．经济困难

D．社会孤立

E．以上均是
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单项选择题

Questions from 31 to 35 are based on the following passage: Negotiations work wonders. This is particularly so in international business since it is mostly through negotiations that exporters and importers bridge their differences and reach a fair and mutually satisfactory deal. By presenting a more comprehensive negotiating package in a well planned and organized manner, exporters should be able to improve the effectiveness of their business discussions and in the long term the profitability of their export operations. To avoid being confronted by costly demands, an exporter should try to determine the buyer’s real interest in the products from the outset. This can be ascertained through appropriate questions but must also be based on research and other preparations before the negotiations. Only then can a suitable counter-proposal be presented. To achieve a favorable outcome from the negotiations, an exporter should draw up a plan of action beforehand, which addresses a few key issues. Experienced negotiators consider that as much as 80% of their overall time devoted to negotiations should go to such preparations. The preliminary work should be aimed at obtaining relevant information on the target market and the buyers of the products. It should also include developing counter-proposals if objections are raised on any of the exporter’s opening negotiating points. The preparations should thus involve formulating the negotiating strategy and tactics.In international marketing negotiations, it is advisable for small and medium-sized exporters not just to limit their discussions to pricing issues, although pricing is a key factor in any business transaction, exporters should give more attention to the full range of marketing factors. They should stress the strengths of their firms and products and match them with the perceived needs of the buyers. Once these issues have been covered, they can consider the question of price and are able to develop a profitable business.

In international marketing negotiations,（）always come first.

A．prices

B．full range of marketing factors

C．manufacturing costs　

D．customers’ needs
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