Tom's mother is at home, but she is not (1) in||on||at the kitchen. She usually waters the vegetables in the garden (2) in||on||at the moming.
Tom's father is (3) at||in||on work, but he isn't in his office at the moment. It is his lunch break and he is (4) at||in||on a travel agent's, looking at holiday brochures.
Tom is usually at school at this time, but he has a bad cold today. He has nothing to do but lying (5) on||at||in the sofa and looking at the posters (6) on||at||in the wall.