0 to find something or someone after looking for it, him, or her in a lot of different places -- 追蹤到;追查到
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。