Задать 5 вопросов к предложению. They know each other

Question

Задать 5 вопросов к предложению.
They know each other

Answer 1

Do they know each other?(special)
Do they know each other or those boys?(alternative)
Whom do they know?(special)
they know each other,do not they?(disjunctive)
who knows each other?(question to the object)