1. General question (общий вопрос)
Have my parents visited America this spring?
2. Alternative question (альтернативный вопрос с “or”)
Have my parents visited America or Australia this spring?
3. Tag question (разделительный вопрос, с хвостиком)
My parents have visited America this spring, hasn't they?
4. Special question (специальный вопрос)
When have my parents visited America this spring?
5. Question to the subject (вопрос к подлежащему)
Who have visited America this spring?