Imagine that you have plenty of milk but no bread, 想象一下，你有很多牛奶却没有面包，

　　you know that your sister had some bread but she doesn't drink milk, 你知道你妹妹有面包，但她不喝牛奶，

　　she won't trade your milk for her bread, 她不会用她的面包换你的牛奶，

　　and your brother doesn't have any milk but he has some fruit, 你哥哥没有牛奶，但他有一些水果，

　　your sister loves fruit, then what will you do? 而你妹妹喜欢水果，你会怎么做？

　　You will probably trade your milk for his fruit, and trade that fruit for bread, this is called a triangle trade. 你可能会用你的牛奶交换他的水果，再用水果交换面包，这被称为三角贸易。

　　When people didn't use any paper money or gold, they traded things. 当人们没有使用纸币或黄金的时候，他们会交换东西。

　　Triangle trade means that three groups trade things with each other. 三角贸易指的是三个群体互相交换东西。