0 a chemical bond in which two atoms share one or more pairs of electrons that hold them together -- 共價鍵(原子間共用電子而形成的化學鍵)
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。