In the 13^th century, the famous Indian traveller, Marco Polo, travelled a long way to China. He saw many wonderful things. One of the things he discovered was that Chinese used paper money. In western countries, people did not use paper money until the 15^th century. However, people in China began to use paper money in the 7^th century.
A Chinese man called Cai Lun invented paper almost 2,000 years ago. He made it from wood. He took the wood from trees and made it into paper. He then put these pieces of paper together and made them into a book.
Now paper still comes from trees. We use a lot of paper every day. If we keep on wasting so much paper, there will not be any trees left on the earth. If there are no trees, there will be no paper. 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 nearly 48,000 trees every day. Since it takes more than 10 years for a tree to grow, we must start using less paper now. If we don’t, we will not have enough time to grow more trees to take the place of those we use for paper.
So how can we save paper? We can use both sides of every piece of paper, especially when we are making notes. We can also use cotton handkerchiefs（手帕） and paper ones. When we go shopping, we can use fewer paper bags. If the shop assistant does give us a paper bag, we can save it and refuse (拒绝) it later.
Everyone can help to save paper. If we all think carefully, we can help protect trees. But we should do it now, before it is too late.
【小题1】When he was in China, Marco Polo __________ .

Li Dong is a farmer. He has a very big   46 . On the farm, he grows oranges, grapes and bananas. Many people come to   47  his farm. He is a successful young man and becomes very famous.
In 2003, he went back to his hometown   48  he finished middle school. “What work can I do?” he said to himself. Then he had an idea. “I’m interested   49  farming. I can grow fruit!” He began to watch many   50  on TV about growing fruit. He also read a lot of books about it. Then he went to   51  on Mr Wang’s farm for two years. He learned a lot there.
In 2005, he started his own fruit farm.   52 , Li Dong’s farm was small. But now, his farm is much   53 . His fruits are very good. He sends them to many big   54  in China, such as Shanghai, Beijing and Guangzhou. He also grows vegetables and raises chickens on his farm. His family eats very   55  food. He has a very happy family.