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.

不属于Ⅰ型超敏反应的是

A．支气管哮喘
B．药物过敏性荨麻诊
C．过敏性鼻炎
D．过敏性休克
E．血清病