根据下列短文内容，在短文后的空格处填上一个恰当的词，使短文完整、通顺。

We usually use _ 76__ kinds of money. One kind is money made of paper and the other kind is money made of metal.  But in the past people used many things   77  of money. Some countries used salt, tea or stones. Other countries even used some animals. Today people in some places in the world   78  do not use paper money all the time.

On the island of Yap, people use the   79  money in the world —Yap stones . These are round, white stones   80  a hole in the middle. The Yap stones do not   81  from this island. The Yap men have to go to the islands over 600 kilometres away to get   82    

Rich people do not carry the heavy Yap stones. Servants    83  the rich. Today people on the island of Yap use paper money for everyday shopping. But for other things they still   84 Yap stones to   85  money.