They are at school.утвердительное)
They aren't at school.(отрицательное(частичка not)
Are they at school?(вопросительное)
They are at school.
Отрицательное:
They are not at school.
Вопросительное:
Are they at school?
They are at school.утвердительное)
They aren't at school.(отрицательное(частичка not)
Are they at school?(вопросительное)