3. A: Is it a blackboard? B: No, it isn't. It's a blackboard.

Перевод задания: Дополните диалоги по образцу.

A: Is it a blackboard? (Это доска?)
B: No, it isn't. It's a blackboard. (Нет. Это доска.)

Ответ: Is it a blackboard? — No, it isn't. It's a blackboard.