1) Please don't laugh at him. I feel sorry for him.
2) The room was full of children's happy laughter.
3) Young children must travel in the back of the car.
4) Jack had a big family. In fact he had six sisters and brothers.
5) I'm so proud of you: you've done all the work on your own.
6) We were surprised at the new school rules.
7) Sue couldn't see us because she was standing with her back to us.
8) The film was so funny that I laughed out loud.
9) A backpack is a backpack because you carry it on your back.
10) John was very tall and usually sat at the back of the classroom.
Ответ: at, of, in, in, on, at, with, out, on, at