Nick (not have to commute to work) everyday if he (work) from home.
Nick WOULDN'T have to commute to work everyday if he WORKED from home.
If they (not have) such a noisy dog, they (get on) better with their neighbours.
If they DIDN'T HAVE such a noisy dog, they WOULD GET ON better with their neighbours.
I (not buy) that bike if I (be) you, it's too expensive.
I WOULDN'T BUY that bike if I WERE you, it's too expensive.