1. There isn't a cat in the garden.
2. There aren't three posters in the bedroom.
3. There isn't a girl in the playground.
4. There isn't a boy playing football.
5. There aren't apples in the supermarket.
6. There isn't a computer in the classroom.
7. There aren't cows in the farm.
8. There aren't twenty days in a month.
9. There isn't a ruler on the table.
10. There isn't a monkey at the zoo.