库存货物发生质量变化，是由一定因素引起的。物品的物理性质、机械性质、化学性质等都属于

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.

补出下列名句名篇中的空缺

1．吾恐季孙之忧，不在颛臾，                  。（《论语·季氏将伐颛臾》

2．谨庠序之教，                    。（《孟子·寡人之于国也》

3．青，          ，           ；冰，水为之，          。（荀子《劝学》）

4．故木受绳则直，                ，                    ，则知明而行无过矣。（荀子《劝学》）

实验室用大理石（主要成分是CaCO₃）与盐酸（HCl）反应制取二氧化碳，现有10g大理石与过量盐酸反应，可制得多少克的二氧化碳？同时生成氯化钙的质量是多少？

近年的煤气价格大幅上升，而且煤气使用安全隐患较多，为此很多市民的家里都改为使用电热水器来加热水．下图是一台电热水器的铭牌，请你根据铭牌提供的信息进行计算：

额定容积/L	50
额定电流/A	10
额定电压/V	220
净重/kg	30
安全等级	1级

（1）此电热水器的额定电功率；

（2）此电热水器在额定电压下工作1h，要消耗电能多少度？

（3）假如电热水器加热时没有能量的损耗，则上一问中电热水器能将水温升高多少？（结果保留整数，ρ_水=1000kg/m³，C_水=4.2×10³J/（kg•℃））

络合滴定曲线描述了滴定过程中溶液pH变化的规律性。