you're wasting your time
Je pense que tu perds ton temps.
I think you're wasting your time.
Tu perds ton temps à essayer de convaincre Tom.
You’re wasting your time trying to convince Tom.
Ne le leur explique pas ; tu perds ton temps.
Don't explain it to them; you're wasting your time.
Tu perds ton temps à essayer de le convaincre.
You're wasting your time trying to convince him.