0 one of a row of large, flat stones on which you can walk in order to cross a stream or river that is not deep -- (溪流或河流中的)踏脚石,垫脚石
1 an event or experience that helps you achieve something else -- 进身之阶;敲门砖,垫脚石,跳板
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。