помогите пожалуйста исправить предложения!!очень надо заранее спасибо)))

1. I THINK that he will be late tomorrow
2. I have been learning the new words for ten HOURS
3. They discussed everything two days ago
4. Natasha can't go. She HASN'T finished her work yet
5. Those girls translated Part Two last Monday
6. She has BEEN cooking lunch for an hour
7. I don't know the boy. I HAVE never met him