PREP1语法30

小皮球PAL

The rise of the Incan empire rested not only on the Incas' military might and the ability of their rulers but also on their imposition of a highly organized economic and political system on many different ethnic groups, who were permitted to retain many of their customs and often their own leaders.

红线部分是正确句子，修饰成分紧跟修饰对象，WHO修饰了GROUPS，为什么中间还可以加逗号，不是说这样的话逗号就不需要的吗？

kiwifoodtown

非限定定语从句，前面加逗号。

MiaZhang

貌似定语从句引导词里面只有that不能引导非限定性定语从句，其他引导词在引导非限定性定语从句时候前面需要有逗号