题目内容：

    In the 13th century, Marco Polo, the world known Italian traveller, saw many wonderful things in China. One of the things he discovered was money made of paper. People in the West did not have such kind of money until the 15th century. 1.

Paper was invented by a Chinese man called Cai Lun almost 2,000 years ago. But it was not made in Europe until the year 1100. Four hundred years later, a German discovered that he could make the best paper from trees. 2.

Paper can be used in many ways. The common uses include newspapers, magazines and books. But do you know that paper can be used for keeping warm? In Finland, the farmers wear paper boots to keep their feet warm in the snow. And even houses can be insulated (使绝缘的) from heat or cold with paper.

However, we have to understand that paper still comes from trees now.  3. Every day people throw away about 2,800 tons of paper in our city. It takes 17 trees to make one ton of paper. This means that we are cutting down nearly 48,000 trees every day. The fact is that it takes more than 10 years for a tree to grow.

4. We can use both sides of every piece of paper. We can make useful things out of used paper. We can use china cups instead of paper ones. When shopping, we can use fewer paper bags and reuse them if we have some.

In short, we should keep a balance (平衡) between using paper and protecting trees, and do it now before it is too late.

A.So we must start saving paper right now.

B.If we keep on wasting so much paper, there will not be any trees left on the earth some day in the near future.

C.However, the Chinese began to use it in the 7th century.

D.So it is the right time to stop making paper from trees.

E.After that, countries rich in forests, such as Canada, Sweden, America, Finland became the most important ones in paper making.