Today anyone will accept money in exchange for goods and services. People use money to buy food, furniture, books, bicycles and hundreds of other things we need or want. When they work, they usually get paid in money. Lots of the money today is made of paper. But people used to use all kinds of things as money. One of the first kinds of money was shells. Shells were not the only things used as money. In China, cloth and knives were used. In the Philippine Islands, rice was used as money for  a long time. Some Africans once used elephant tusks, monkey tails, and salt as money. The first metal coins were made in China. They were round and had a square hole in the center. Different countries have used different metals and designs for their money. Later, countries began to make coins of gold and silver. But even gold and silver were inconvenient if you had to buy something expensive. Again the Chinese thought of a way to improve money. They began to use paper money. The first paper money looked more like a note from one person to another than the paper money used today. Money has had an interesting history, from the days of shell money until today. We can infer from the passage that   _  .
paper money isn't difficult to make money must be suited to carry people need money to exchange goods with each other people prefer metal coins to paper notes