0 a type of squirrel (= a small mammal with a long tail that climbs trees) that has skin joining its front and back legs so it can travel short distances through the air -- 飞鼠(一种松鼠)
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。