TURN FROM ACTIVE INTO PASSIVE

1.they sell apples by the kilo
2.they keep milk in the fridge
3.her father gave her a watch for her birthday
4.they are still writing letters
5.they will bring the parcel to the office
6.he has made mistakes in the test
7.somebody has left the window open
8.she painted that picture ten years ago
9.they will prepare all the papers for you
10. she has made a nice dress herself
11.they will discuss these problems at the meeting
12.many people are watching the final match now
13.they understood his words correctly