https://learnenglish.britishcouncil.org/skills/writing/upper-intermediate-b2/a-covering-email
I wish, If only.
Wishes about the present
We use wish with past Tense forms (simple and continuous) to express regret about present situations:
- I wish I was taller = (I’m not very tall)
- I wish I was going with you = (but I'm not)
I wish you were more help. = (you are not) I wish I were can replace I wish I was.
To many people, I wish I were sounds more correct:
I wish I were taller.
We use wish with could to express a wish for a present situation to be different:
I wish I could use a computer well.
X I wish I would tell her about it.
I wish I could tell her about it.
Past Simple > present>I wish I knew the answer. (= I don’t know)
Past Simple > present > I wish I was /were better at sports. (= I'm not)
Past Continuous > present > I wish I was /were going with you. (= I'm not)
Could > present > I wish I could give you an answer. (= I can't)
Would > future > I wish you would be quiet. (= Your talking irritates me.)
Past Perfect > past > I wish I had known you then. (= but I didn't)
Could have > past> I wish I could have explained. (= I wasn't able to)
Wishes about the future
We use wish with would to say how we would like somebody to behave in the future:
/I wish you would stop talking.
/I wish they would stop arguing.
• We can also use this pattern in situations that do not involve people:
I wish this car would go faster.
Wishes about the past
We use wish with the Past Perfect when we have
Regrets about the past:
I wish I hadn't taken your advice. (= but I did)
I wish she could have come. (= but she didn't)
If only
If only can be more emphatic than I wish. The verb forms after if only are the same as the patterns with wish:
If only I had more money! (= but I haven't)
If only I was going on holiday with you!
If only you were here. (= but you re not)
If only the sun would come out!
If only you could be here! (= but you're not)
If only I'd listened to you! (=but I didn't )
If only he could have explained! (=but he wasn't able to)
