In this basic English grammar lesson, learn how to form questions with IS and DOES. Both IS and DOES are common question structures. The best way to know if you need IS or DOES depends on the structure of the sentence. It's easier to know if it's IS or DOES when you see the sentence in a positive statement instead of a question. In the positive statement, if your main verb is the verb "to be", then you need to use "to be" in the question. You simply invert the subject and the verb to form a ques