问题
单项选择题
Where does a barter take place
A．Where there is only salt.
B．Where the people's trading needs are fairly simple.
C．Where metal tools are used.
D．Where money is unknown.
答案
参考答案：B
解析：根据文章的第二段的第一句中commerce usually means barter．以及There is a direct exchange of goods可以推出barter是以物易物的意思。