We have eaten a tasty breakfast.
Have we/you eaten a tasty breakfast? - общий вопрос
We have eaten a tasty breakfast, haven't we? - разделительный
Who has eaten a tasty breakfast? - к подлежащему
Have we eaten a tasty breakfast or a tasty lunch? - альтернативный
What have we/you eaten? - специальный
What breakfast have we eaten? - специальный