题目内容：

When we think of money, we think of coins and paper bills. That is what money is today. But in the past people used many things instead of money. Some countries used cows. Other countries used salt, tobacco or stones. Today there are still some places in the world that do not use paper money. One place is the island of Yap in the Pacific Ocean.

On the island of Yap, people use the heaviest money in the world—Yap stones. These are round, white stones with a hole in the middle. They do not originate(起源)from the island. The Yap men have to go to the islands four hundred miles away to get them. Big stones can be twelve feet high as big as two tall men. Small stones are as big as a dinner plate.

Rich people do not carry the Yap stones. Servants follow the rich. Each servant carries a stone or a long stick over his shoulder. Today the people on the island use paper money for everyday shopping. But for other things they still prefer Yap stones.

1.What is money today?

2.What did people use instead of money in the world in the past?

3.Where do people on the island of Yap get Yap stones?

4.What do Yap stones look like?

5.What do the Yap men buy with Yap stones today?