Correct the following sentences:
1. I had ought to have studied harder.
2. You ought to do it, hadn't you?
3. Hadn't you ought to have gone?
4. Yes, I had ought to have gone yesterday.
5. Do you think I had ought to have accepted?
6. He had ought to come to-morrow.
7. The tickets had ought to have come from the printer's yesterday.
8. We had not ought to stay out so late.