题目

这后半段不会分析成分 toward the concentration of the poor of the American society into the cities.
Long before this century started,there had begun a trend toward the concentration of the poor of the American society into the cities.主要是后半段

提问时间：2021-10-14

答案

there had begun a trend 是主干
a trend toward the concentration 集中的趋势
the concentration of the poor穷人的集中
the poor of the American美国的穷人
意即美国穷人涌向城市的趋势