化学用语是学习化学的重要工具，按要求用化学用语填空；

（1）2个氮分子____ ；

（2）2个硫酸根离子____ ，

（3）医疗上用来治疗胃酸过多的一种盐____ ，

（4）常用于改良酸性土壤的一种碱____ ．

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    People call the Winter Olympics the White Olympics. At this time, they publish(发行) many stamps to mark(标志) the great games. The first stamps came out on January 25th, 1932 in the United States for the 3rd White Olympics. From then on, publishing stamps during the White Olympics became a rule.

    During the 4th Winter Olympics, people published a group of stamps in November 1936. They drew five rings of Olympics. It was the first time that the rings appeared(出现) on the stamps of the White Olympics.

    In the 1950s，the stamps of this kind became more colorful. When the White Olympics came, the host countries as well as non-host countries published stamps to mark those games. China also published four stamps in February 1980 when the Chinese sportsmen began to take part in the White Olympics.

    In Asia, Japan was the only country to hold the White Olympics. They sold 14,500 million stamps during the Olympics.

    People drew different kinds of sports on these small stamps, and they enjoyed the wonderful sports and some famous players.

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