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  3. The earliest process of making paper was done almost 5,000 years ago in Egypt and the Nile Valley. In those days, paper was made

The earliest process of making paper was done almost 5,000 years ago in Egypt and the Nile Valley. In those days, paper was made

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问题     The earliest process of making paper was done almost 5,000 years ago in Egypt and the Nile Valley. In those days, paper was made from strips of the papyrus plant.
    Modern paper-making began in China about 2,000 years ago. This process produced paper from cloth, straw, wood or the bark of trees. The raw materials are struck over and over until they become loose. Then they are mixed with water.
    After the water has been removed, the flat, thin form remaining is permitted to dry. This becomes a sheet of paper.
    Large machines started to be used for making paper near the end of the 16th century. Today, paper-making is a big business. But it is still possible to make paper by hand, since the steps are the same as using big machines.
    You should choose paper with small amounts of printing. Old envelopes are good for this reason. Colored paper also can be used, as well as small amounts of newspaper. Small pieces of rags or cloth can be added. These should be cut into pieces about 5 centimeters by 5 centimeters.
    Everything is placed in a container, covered with water, and brought to a boil. It is mixed for about 2 hours with some common chemicals and then allowed to cool. Then it is left until most of the water dries up. The substance left, called pulp, can be stored until you are ready to make paper.
    When you are ready, the pulp is mixed with water again. Then the pulp is poured into a special box or mold. The mold is made of small squares of wire that hold the shape and thickness of the paper. To help dry the paper, the mold lets the water flow through the small wire squares.
    After several more drying steps, the paper is carefully lifted back from the mold. It is now strong enough to be touched.
    The paper is smoothed and pressed to remove trapped air. You can use a common electric iron used for pressing clothes.
Whether the paper is strong enough to be touched is determined by_____.
选项 A、how long the pulp is stored
B、how thick the paper is
C、how much water remains
D、what type of chemicals are used
答案C
解析 倒数第2段提及要经过“多次干燥处理”，才能把纸取出，可见，纸是否足够坚韧以便取出，取决于纸浆中含有的水分的多少，因此，本题应选C。
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