I was cleaning rooms at the weekend, but I did not mean that the normal date. I did not clean the room. But the weekend can better clean the room because there was more time. Therefore, it's a clean room.
Clean the room on weekends. But it does not mean normal day. I did not clean the room Only the weekend to clean the rooms better. Because more time The room is clean, too.
I clean the room in the weekend. But I'm not mean regular day. I didn't clean the room. Only the day weekend can clean the room well. Because there are more time.