on each side of the road

题目

on each side of the road
There are a lot of people on (each) side of the road.
其中为什么要填each?在其它的情况下有没有别的关于 on ( )side of 的用法?

答案

on (each) side of the road= on (either) side of the road= on (both) sides of the road 在路的两旁