Active -> passive: John cleaned the bathroom.
The bathroom was cleaned (by John)
Active -> passive: The teacher closes the window.
The window is closed by the teacher.
Active -> passive: Snow covered the mountains.
The mountains were covered by snow.
Active -> passive: We keep milk in the refrigirator.
Milk is kept in the refrigerator.
Active -> passive: They clean the windows every week.
The windows are cleaned every week.
Active -> passive: A snake bit me.
I was bitten by a snake.
