问题 填空题


International free trade occurs when there are no barriers to trade. Countries can get a lot of benefits from free trade. (31) , all countries choose to adopt protection policies to some extent In this essay, I will give (32) of the arguments in favour of world free trade, describe the methods for the trade protection policies (33) countries erect to protect domestic industries and give the arguments which can be put (34) to justify protectionist policies.
Tariffs are taxes on (35) products. Sometimes, tariffs are known (36) imports duties and customs duties. They can be used (37) raise revenue. But, they are usually used to (38) imports and also to help domestic producers. The effect of imposing (39) tariff is to raise price for domestic consumers, and some consumers will switch consumption (40) imported goods to domestically produced substitutes. (41) are two types of tariffs. One is percentage taxes, it is based on
percentage of value of goods. (42) one is specific (fixed sum taxes), it is based on a fixed tax (43) unit or weight. Quota is a limit on the supply of goods or services. It can be imposed on exports. The domestic market share will increase because of (44) a limit on the quantity of imported goods. However, the price of protected goods will also rise because a quota is to reduce supply. Voluntary export restraint or restriction (45) similar to a quota, but this time the limit on imports arises from a voluntary agreement (46) the exporting and importing countries. For example, the UK had an agreement with Japanese car (47) that they should not take (48) than 10 percent of the UK car market. Exchange control means that a government control on foreign currency controls importers access to foreign currency. This is a (49) which was used by a number of European countries, (50) the UK, in the 1960s and 1970s and is still found in some developing countries.

答案

参考答案:between

单项选择题
实验题

以下是某同学测定硫酸铜晶体(CuSO4·xH2O)中结晶水含量的实验方案。

实验用品:硫酸铜晶体、研钵、干燥器、坩埚、三脚架、玻璃棒、药匙、托盘天平

实验步骤:

① 准确称量一个干净、干燥的坩埚;

② 在坩埚中加入一定量的硫酸铜晶体试样,称重,将称量的试样放入研钵中研细,再放回到坩埚中;

③ 将盛有试样的坩埚加热,待晶体变成白色粉末时,停止加热;

④ 将步骤③中的坩埚放入干燥器,冷却至室温后,称重;

⑤ 将步骤④中的坩埚再加热一定时间,放入干燥器中冷却至室温后称量。重复本操作,直至连续两次称量的质量差不超过0.1g为止;

⑥ 计算硫酸铜晶体化学式中x的实验值。

分析该方案并回答下面问题:

(1)完成本实验还需要的实验用品是___________ ;

(2) 指出实验步骤②中存在的错误并改正:_______________ ;

(3)硫酸铜不能放置在空气中冷却的原因是 _______________;

(4)步骤⑤的目的是________________ ;

(5)若坩埚的质量为m,坩埚与硫酸铜晶体的质量为m1,加热后称量坩埚与无水硫酸铜的质量为m2,则晶体CuSO4·xH2O中,x =______________ (写表达式);

(6)下面的情况有可能造成测试结果偏高的是 ____________(填序号)。

A.试样中含有加热不挥发的杂质

B.试样中含有加热易挥发的杂质

C.测试前试样已有部分脱水

D.实验前坩埚未完全干燥

E.晶体加热脱水不完全

F.加热时有晶体溅出