могу помочь только с первым и четвертым, в остальных я не уверена. sorry
1.
1.They haven't finished their work yet.
2. We went to the cinema last month.
3. We had dinner very early yesterday
4. Mum already has cooked the dinner
5. I can't find my key. I think I have lost it.
4.
1. your
2. mine
3. his
4. hers
5. ours
6. theirs