1. Have you finished your report?
2. Can cats climb trees?
3. Must I go to bed now?
4. May I have a slice of pie?
5. Can you return your library book?
An auxiliary verb (also known as a helping verb) helps the main verb by giving the sentence a sense of time. For example, the auxiliary verb "will" tells the reader that whatever the main verb action is, it will be in the future. The auxiliary verb is found between the subject and the main verb in a sentence. To form a question, the auxiliary verb can move before the subject. A sentence can have more than one auxiliary verb.