Answer:
1. it’s possible that joe will go to university - Joe might go to university.
2.I’m not sure that you’ll enjoy the party - You might not enjoy the party.
3. It’s possible that Karen won’t come with us - Karen may not come with us.
4.I have a feeling that the exam will be difficult - The exam may be difficult.
5.I’m not sure that the weather will be good tomorrow - The weather may not good tomorrow.
6.Perhaps Dad won’t agree - Dad might not agree.