Study this example situation:
Sarah wants to phone Paul, but she can't do this because she doesn't know his number. She says:
If I knew his number, I would phone him.
Sarah says: If I knew his number .... This tells us that she doesn't know his number. She is imagining the situation. The real situation is that she doesn't know his number.
When we imagine a situation like this, we use
if + past (
if I
knew /
if you
were /
if we
didn't etc.). But the meaning is present,
not past:
- There are many things I'd like to do if I had more time. (but I don't have time)
- If I didn't want to go to the party, I wouldn't go. (but I want to go)
- We wouldn't have any money if we didn't work. (but we work)
- If you were in my position, what would you do?
- It's a pity he can't drive. It would be useful if he could.