1. - 2. to 3.-
________
1. If he has a toothache, he'll go to the dentist
If he had a toothache, he would go to the dentist
If he had had a toothache, he would have gone to the dentist
2. They will wait until he comes back
They would wait until he came back
They would have waited until he had come back
3. I will give you the book if I find it
I would give you a book if i found it
I would have given you a book if i had found