0 a piece of paper given by a shop when you return something you do not want, that allows you to buy other goods of the same value -- 換貨憑單，信用票據（退貨時商店給的票據，可用於換取等值的其他商品）
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。
