Исправь предложения. к примеру;its a book.-it isnt a book. its an exercise.

 1) Its an exercise. - It isnt an exercise.  2) Theyre chairs - They arent chairs. 3) Its a blackboard. - It isnt a blackboard. 4) Theyre old. - They arent old. 5) Its brown.- It isnt brown. 6) Theyre comfortable. - They arent comfortable. 7) Its a pen. - It isnt a pen.