Rewrite the sentences using the modals (present or past)
1.I'm sure that John ate the cake.
2.Perhaps I'll go to Vienna next spring.
3.I'm sure that your neighbours aren't rich.
4. It's possible that Paul forgot about our anniversary.
5. I'm certain Paul didn't steal it. I was with him all time yesterday.
6. I think they are not tired.
7. Perhaps Ann wasn't at home.