Question

Which sentence is punctuated correctly?

I used the green pen, not the red one for my homework.
I used the green pen, not the red one, for my homework.
I used the green pen not the red one for my homework.

Answer 1

2nd one is correct.

Answer 2

the comma is pretty much like a little pause. When saying this, you would take a little pause after " pen " and after " one ".

Answer 3

ok thank you

Answer 4

anytime :)