0 a seat that can throw out the person flying an aircraft if they suddenly have to leave it because they are in danger -- (危急情况下将人从飞机中弹出的)弹射坐椅
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。