问题
实验题
碳酸钙在高温下煅烧一段时间后，得到白色固体（CaCO3
CaO＋CO2↑），为了确定白色固体的成分，对其可能的组成进行探究，请你完成下表。（至少说出两种猜想但可以只验证一种猜想）
答案
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碳酸钙在高温下煅烧一段时间后，得到白色固体（CaCO3CaO＋CO2↑），为了确定白色固体的成分，对其可能的组成进行探究，请你完成下表。（至少说出两种猜想但可以只验证一种猜想）
请认真阅读下列短文，并根据所读内容在文章后76~85表格中的空格里填入一个最恰当的单词。 注意：每个空格只填1个单词。请将答案写在答题卡上相应题号的横线上。 In the past, man did not have to think about the protection of his environment. There were not many people on earth, and natural resources seemed to be unlimited. Today, things are different. The world has become too crowded. We are using up our natural resources too quickly, and at the same time we are polluting our environment with dangerous chemicals. If we continue like this, human life on earth will not survive. Everyone realizes today that if too many fish are taken from the sea, there will soon be none left. Yet, with modern fishing methods, more and more fish are caught. We know that if too many trees are cut down, forests will disappear and nothing will grow on the land. Yet, we continue to use bigger and more powerful machines to cut down more and more trees. We realize that if rivers are polluted with waste products from factories, we will die in the end. However, in most countries waste products are still put into the sea, and there are few laws to stop this. We know, too, that if the population of the world continues to rise at the present rate, in a few years, there will not be enough food. What can we do to solve these problems? If we eat more vegetables and less meat, there will be more food available for everyone. Land that is used to grow crops can feed five times more people than land where animals are kept. The world population will not rise so quickly if people use modern methods of birth control. Finally, if we educate people to think about the problems, we shall have a better and cleaner planet in the future.
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