People ____ the paper ____ wood.

    "All work and no play makes Jack a dull boy" is a popular saying in the USA．It is true that all of us need recreation (娱乐). We cannot work all the time if we are going to keep good health and enjoy life.

    Everyone has his own way of relaxing. Perhaps the most popular way is to take part in sports. There are team sports, such as basketball and football. There are also individual(个人) sports, such as swimming and running. Skating and mountain climbing are the most popular recreations for people who likes to be outdoors.

    Not everyone who enjoys sporting events likes to take part in them. Many people like watching TV or listening to them on the radio. So many people like forms of indoor recreation, such as watching TV, singing and dancing.

    It doesn't matter we like indoors recreation or take part in outdoor sports. It is important for everyone to relax from time to time, and enjoy some forms of recreation.

请回答下列问题：

（1）﹣定温度下，向0.1mol/LCH₃COOH溶液中加入少量CH₃COONa晶体时，下列说法正确的是____ ．（填代号）

a．溶液的pH减小 b．CH₃COOH的电离程度减小

c．溶液的导电能力增强  d．溶液中c（OH^﹣）•c（H⁺）不变

（2 ）25°C 时，0.10mol/L Na₂CO₃ 溶液的 pH=11，则溶液中由水电离出的 c（OH^﹣）=____ mol/L．

（3）己知快K_sp只与温度有关，溶解平衡：CaCO₃（s）⇌Ca²⁺+（aq）+A^2﹣（aq）△H＞0．

①温度升高时，K_sp____．（填“增大”“减小”或“不变”，下同）

②向浊液中通入HCl气体c（ Ca²⁺）____ 

（4）己知醋酸的电离常数k=1.8×l0⁵．25°C时，向CH₃COOH溶液中加入一定量的NaHCO₃，所得混合液的 pH=6，则混合液中 c（CH₃COO^﹣）/c（CH₃COOH）=____ ．

“1625年，运往欧洲的棉布为2215匹，到17世纪末，这项贸易直线上升，棉织品不仅比毛织品轻，而且便宜……这是一种销售范围很广、需求量大的商品，它足以带动一场工业革命。”该材料主要说明的是（  ）