0 a method of buying something new by giving something you own as part of the payment for it -- 折价贴换交易，以旧折价换新
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。
