0 to fail to do as much work or pay as much money as you should by a particular time -- 落後,拖延;拖欠
She got behind with her mortgage and the house was repossessed. 她拖欠抵押貸款,房子被收回去了。
We can complete it step by step however long the road is and it can't be completed however short the road is if you don't even mark your footprint.
再长的路,一步步也能走完,再短的路,不迈开双脚也无法到达。