3. There is/are four armchairs in the living room. 4. There is/are children in the garden. 5. Where is/are the babies? 6. Where is/are the mirror? 7. Where is/are your toy box? 8. Where is/are you?

Смотри, тут всё просто: нужно выбрать правильную форму глагола to be – is или are. Is используем с единственным числом, а are – с множественным. Логика такая:

1. There are four armchairs in the living room.
2. There are children in the garden.
3. Where are the babies?
4. Where is the mirror?
5. Where is your toy box?
6. Where are you?