Statistics are unreliable, but perhaps 200m rural migrants are working in urban areas, with some 20m children. Many more children are left behind, in the care of relatives.

据不完全统计，有大约2亿来自农村的外来务工人员在城市工作，有2千万儿童跟随父母来到城市，更多的孩子被留在家乡，由亲戚照顾。

youdao

While the goals behind No child Left behind were admirable, experience has taught us that the law has some serious flaws that are hurting our children instead of helping them.

然而，没有一个孩子被落下的目标是很好的，经验告诉我们法律存在同样严重的毛病，在伤害他们而不是在帮助他们。

youdao

Some families also face heavy legal bills when they adopt children left behind.

BBC: Hidden costs to crime victims

The next afternoon two of the children showed up at my hotel to give me some papers I had left behind in taxi.

FORBES: A Week in Brazil, Pt. 5: Gamboa