Using points and examples from the talk, explain the two definitions of money presented by the professor.
请用讲话中所涉及到的例子和观点，来解释教授提及到两种关于货币的定义。

Now listen to part of the talk in the economical class.
现在，请听某经济课上的部分讲话内容。
So, let's talk about money. What is money?
所以，下面让我们来说一说货币。什么是货币？
Well, typically, people think of coins and paper bills as money.
呃，通常情况下，人们会想到硬币，以及纸币。
But that is using a somewhat narrow definition of the term.
但是，这里用的是货币的狭义定义。
A broad definition is this: money is anything that people can use to make purchases with.
广义上的定义是：货币是任何人们可以用来购买其他物品的物品。
Since many things can be used to make purchases, money can have many different forms.
由于很多东西都可以用来购买东西，所以货币可以有很多不同的形式。
Certainly, coins and bills are one form of money.
可以确信的一点是，硬币和纸币都是货币的一种形式。
People exchange goods and services for coins or paper bills
人们通过交换物品或者服务来获取硬币或者纸币，
and they use this money these bills to obtain other goods and services.
然后他们又用这些货币，这些纸币去换取别的物品以及服务。
For example you might give a taxi driver five dollars to purchase a ride in his taxi.
举个例子，你付给的士司机5美元，用以购买坐他车行驶的一段路程。
And he in turn gives the five dollar to a farmer to buy some vegetables.
然后，他把这五美元付给了某位农民，用以购买一些蔬菜。
But as I said, coins and bills are not the only form of money under this broad definition.
但是就像我之前提到过的那样，硬币和纸币只是在广义定义下，货币的一种形式。
Some societies make use of a barter system.
在一些社会体系中，人们使用的是物物交换制。
Basically, in a barter system, people exchange goods and services directly for other goods and services.
基本上，在物物交换体系中，人们直接用物品或者服务来换取其他的物品或者服务。
The taxi driver, for example, might give a ride to a farmer in exchange for some vegetables.
举个例子，的士司机给捎农民一程，用以交换一些蔬菜。
Since the vegetables are used to pay for a service,
因为蔬菜在这里是用以支付乘车服务的，
by a broad definition the vegetables are used in barter as a form of money.
所以在广义下，蔬菜是物物交换系统里一种形式的货币。
Now as I mentioned there is also a second, a narrower definition of money,
现在，就如我之前提到的第二种，货币的更为狭义的定义。
in the United States, only coins and bills are legal tender,
在美国，只有硬币和纸币才是合法的货币。
meaning that by law, a seller must accept them as payment.
意思是，在法律规定下，卖方必须接受通过它们完成支付行为。
The taxi driver must accept coins or bills as payment for a taxi ride, okay?
出租车司机必须接受用硬币或者纸币来支付打的的费用，对吧？
But in the U.S, the taxi driver is not required to accept vegetables in exchange for a ride.
但是在美国并没有要求出租车司机接受用蔬菜交换行程的支付方式。
So a narrower definition of money might be whatever is legal tender in a society,
所以，货币的狭义定义是指，在社会中，只要是合法的，
whatever has to be accepted as payment.
能被接受的物品都能称之为货币。