Задать 5 типов вопросов The united states of America is a presidential republic

Are the United States a presidential republic? (Общий) What are the United States? (Специальный) Are the United States a presidential republic, or not? (Альт.) The United States of America are a presidential republic, aren't they? ( Разделительный) What's the presidential republic? (Вопрос к подлежащему)