Написать а пассивном залоге. i buy a new dress. he sent a post card. you planted a tree

I buy a new dress. - A new dress is bought by me.
He sent a post card. - A post card was sent by him.
You planted a tree. - A tree was planted by us. 

1. These cups are dirty.
2. Those biscuits were tasty.
3. These hotels are very expensive but they`re very nice.
4. There are children's playgrounds in the parks.
5. Those are new sepermarkets in our towns.
6. They`re delicious lemon pies for dessert.
7. They`re nice cotton dresses for my nieces.
8. These men are engineers.
9. Those women are my sisters.
10. These children are my sons.
11. Those geese are big.
12. These mice are white.
13. These men are doctors.
14. Those women are my cousins. They are teachers.
15. Those girls are my nieces.

It had been snowing for 4 hours
Eton had been working for 20 years before he retired
Mike had been living there for a tonight
They had been studying German for 5 years before they went to Berlin
The authors had been working on the novel for 2 years before the sent it to a publisher
Pele had been playing football for 6 years before...
The students had been listening attentively to the dialog for an hour ...
The children had been walking for 2 hours..
(вместо точек просто продолжение предложения без изменений)