0 used in questions etc when asking someone to point out, state etc one or more persons, things etc from a particular known group -- welche
1 (used to refer to a thing or things mentioned previously to distinguish it or them from others; able to be replaced by that except after a preposition; able to be omitted except after a preposition or when the subject of a clause) (the) one(s) that -- welche
2 used, after a comma, to introduce a further comment on something -- welche
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.
Wir können es Schritt für Schritt vervollständigen, egal wie lang die Straße ist, und es kann nicht fertiggestellt werden, egal wie kurz die Straße ist, wenn Sie nicht einmal Ihren Fußabdruck markieren.