a)
- I wish I had applied for the computer course. → wish / regret about the past → past perfect
- If only you didn’t spend so much time on your PC. → wish about present / future → present simple
- I wish I could create a webpage. → wish about present / future → past modal
- If only I had bought that MP3 player. → wish / regret about the past → past perfect
We use 'I wish / If only' to introduce wishes.
b)
- I wish / If only I had bought the laptop.
- I wish I had known it was on special offer.
- If only my computer was more efficient.
- I wish its memory wasn’t low.
- If only I could get my work done quickly.