Вставь предлоги in, on, at. 1. The picture is the wall. 2. My desk is front of the window. 3. There is a chair the desk. 4. The carpet is middle of the room.

Решение:

Вставляем предлоги в предложения:

1. The picture is on the wall.
2. My desk is in front of the window.
3. There is a chair by the desk.
4. The carpet is in the middle of the room.

Ответ: on, in, by, in the.