An auxiliary verb, sometimes called a helping verb, is used with the main verb to give grammatical information such as tense or voice.
The main auxiliary verbs are to be, to have, and to do.
Examples of auxiliary verbs expressing tense.
- They were waiting for an hour.
- He has drunk it already.
Examples of auxiliary verbs expressing the passive voice.
- The road is being repaired.
- A letter was written by him.