8. I have sold my old car / My old car has been sold by me.
"My old car has to be sold" means "My old car must be sold".
9. They opened the store only last month / The store was opened by them only last month by them.
This just makes it more natural.
10. We don't permit smoking in the kitchen / Smoking in the kitchen is not permitted (by us).
11. The cat caught the mouse / The mouse was caught by the cat
The past simple form of 'catch' is 'caught'.
12. Your behavior disgusts me / I am distust digusted by your behavior
13. The cat drank all the milk / All the milk was drunk by the cat
14. A stone struck me on the head / I was struck on the head by a stone.