More and more attention has been drawn to the fact that many children are in the countryside when their parents flood into the cities for jobs.
A. left off
B. left aside
C. left out
D. left behind
网友回答
A. left off
B. left aside
C. left out
(答案→)D. left behind
解析：此处left off停止；中断； left aside 不予考虑；. left out 漏掉； left behind永久离开。句意：人们越来越注意到这个事实，当父母涌向城市找工作时，许多孩子被永久的留在乡下。根据句意选D。