1. First Conditional (unit 38)
It’s winter time and very cold. You say:
If it snows tomorrow, I won’t go to work.
There is a real possibility that it will snow.
So here we use the FIRST CONDITIONAL:
If + the present simple, will/won’t in result clause.

2. Second Conditional (unit 39)
You don’t have much money and would like to have more. You say to your friend:
If I won the lottery, I’d definitely give up working and just enjoy my life.
You are imagining a situation that will probably not happen, so we use the SECOND CONDITIONAL:
If + past simple, would/wouldn’t in result clause.

3. Third Conditional (unit 40)
Last month Gary was in hospital for a few days. Rachel didn’t know this, so she didn’t go to visit him. They met a few days ago and Rachel said:
If I had known you were in hospital, I would have gone to see you.
This type of conditional refers to a situation which has already happened in the past but which cannot be changed.
Use If + had + past participle, would have + past participle in the result clause.

4. WISH 1(units 39 and 41)
Use WISH to say that we regret something in the present. In this context we use wish with the past:
I wish I knew what to do about the problem. (but I don’t know and I regret this).

5. WISH 2 (units 40 and 41)
To say we regret something that happened in the past:
I wish I had known about the party. I would have gone if I had known. (but I didn’t).
Use Wish + had + past participle

6. WISH 3 (unit 41)
To complain about a situation or a person that are irritating:
I wish you wouldn’t keep interrupting me.
I wish you would do something instead of just sitting around and doing nothing.
Wish + subject + would/woudn’t and bare infinitive.