这后半段不会分析成分 toward the concentration of the poor of the American society into the cities.

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

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