0 a method used by scientists to discover whether a substance contains metal ions -- 焰色試驗,火焰試驗法(用來測試物質中是否含有某種金屬的方法)
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。