use IF
1. That car is too epensive, so I'm not going to buy it.
2. We don't go shopping very often because we can't afford it.
3. They don't understand the problem. They won't find a solution
4. I can't phone you because I don't know your telephone number.
5. It's raining heavily, so I can't see her on time
use IF
1. That car is too epensive, so I'm not going to buy it.
i would buy that car if it wasn't too expensive
2. We don't go shopping very often because we can't afford it.
We'd go shopping more often if we could afford it.
3. They don't understand the problem. They won't find a solution
if they understood the problem, They would find a solution
4. I can't phone you because I don't know your telephone number.
if I knew your telephone number, I could phone you
5. It's raining heavily, so I can't see her on time
if it wasn't raining heavily, I could see her on time