Sue 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.
Sue 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 you imagine a situation like this, you use if + past (if I knew/if you were/if we didn't etc.). But the meaning is present, not past:
* Tom would read more if he had more time. (but he doesn't have much 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 you can't drive. It would be useful if you could.
B. We use the past in the same way after wish (I wish I knew/I wish you were etc.). We use wish to say that we regret something, that something is not as we would like it to be:
* I wish I knew Paul's phone number. (= I don't know it and I regret this)
* Do you ever wish you could fly? (you can't fly)
* It rains a lot here. I wish it didn't rain so Often.
* It's very crowded here. I wish there weren't so many people. (but there are a lot of people)
* I wish I didn't have to work. (but I have to work)
C. After if and wish, you can use were instead of was (if I were I wish it were etc.). So you can say:
* If I were you, I wouldn't buy that coat. or If I was you...
* I'd go out if it weren't raining. or if it wasn't raining.
* I wish it were possible. or I wish it was possible.
D. We do not normally use would in the if-part of the sentence or after wish:
* If I were rich, I would have a yacht. (not 'If I would be rich')
* I wish I had something to read. (not 'I wish I would have')
Sometimes wish ... would is possible ('I wish you would listen'). See Unit 40C.
E. Note that could sometimes means 'would be able to' and sometimes 'was/were able to':
* You could get a job more easily. (you could get = you would be able to get)
if you could speak a foreign language. (you could speak = you were able to speak)
EXERCISES
38.1 Put the verb into the correct form.
1. If I _knew_ his number, I would phone him. (know)
2. I _wouldn't buy_ that coat if I were you. (not/buy)
3. I --- you if I could, but I'm afraid I can't. (help)
4. We would need a car if we --- in the country. (live)
5. If we had the choice, we --- in the country. (live)
6. This soup isn't very good. It --- better if it wasn't so salty. (taste)
7. I wouldn't mind living in England if the weather --- better. (be)
8. If I were you, --- (not/wait). I --- now. (go)
9. You're always tired. If you --- to bed so late every night, you wouldn't be tired all the time. (not/go)
10. I think there are too many cars. If there --- so many cars (not/be), there --- so much pollution. (not/be)
38.2 Write a sentence with If ... for each situation.
1. We don't visit you very often because you live so far away.
_If you didn't live so far away, we'd visit you more often._
2. He doesn't speak very clearly--that's why people don't understand him.
If he --- more --- people ---
3. That book is too expensive, so I'm not going to buy it.
If the book ---, I ---
4. We don't go out very often because we can't afford it.
5. It's raining, so we can't have lunch in the garden.
6. I have to work tomorrow evening, so I can't meet you.
38.3 Write sentences beginning I wish ...
1. I don't know many people (and I'm lonely).
_I wish I knew more people._
2. I don't have a key (and I need one). I wish ---
3. Ann isn't here (and I need to see her).
4. It's cold (and I hate cold weather).
5. I live in a big city (and I don't like it).
6. I can't go to the party (and I'd like to).
7. I have to work tomorrow (but I'd like to stay in bed).
8. I don't know anything about cars (and my car has just broken down).
9. I'm not lying on a beautiful sunny beach (and that's a pity).
38.4 Write your own sentences beginning I wish ...
1. (somewhere you'd like to be now--on the beach, in New York, in bed etc.)
I wish I ---
2. (something you'd like to have--a computer, a job, lots of money etc.)
3. (something you'd like to be able to do--sing, speak a language, fly etc.)
4. (something you'd like to be--beautiful, strong, rich etc.)