marnujesz czas robiac to

1. You are wasting time doing it.
2. You are wasting time by doing it.
3. You are wasting time with doing it.

a moze jeszcze inaczej ? :)

>1. You are wasting YOUR time doing it.

To na pewno dobrze, reszta raczej nie.

>1. You are wasting time doing it.
jest tez okay

>2. You are wasting time by doing it.
tez jest okay

waste time with/on sth