1. Do my friends usually study well? (общий)
My friends usually study well, don't they? (разделительный)
Who studies well? (к подлежащему)
How do my friends usually study? (специальный)
Do my friends usually study well or bad? (альтернативный)
2. Is she the first-year student?
She is the first-year-student, isn't she?
Who is the first-year student?
What is she?
Is she the first-year or the second-year student?