阅读短文，根据短文内容和已给出的首字母，在空白处填入适当的单词。将完整的单词写在短文后面的横线上。

In the 13^th century, the famous Indian traveler, Marco Polo, traveled a long way to china. D  76   his stay in China, he saw many wonderful things. One of the things he discovered was that the Chinese used paper money. In w  77   countries, people did not use paper money u  78   15^th century. However, people in China began to use paper money in the 7^th century.

A Chinese man called Cai Lun i  79   paper almost 2,000 years ago. He then put these pieces of paper together and made them into a book.

Now paper comes from trees. We use a lot of paper every day. If we keep on wasting so much, there will not be any trees l  80   on the earth. If there are no trees, there will be no paper.  

So how can we save paper? We can use both sides of every piece of paper, e  81   when we are making notes. We can choose drinks in bottles i  82   of those in paper packets. We can also use cotton handkerchiefs and not paper ones. When we go s  83   , we can use fewer paper bags.  If the shop assistant does give you a paper bag, we can save it and reuse it l  84   . 

Everyone can help to save paper. If we all think carefully, we can help to p  85   trees. We should do it now, before it is too late.

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