An auxiliary verb accompanies a main verb to help express its tense, mood, or voice. The most common auxiliary verbs are be, do, and have .

Here are some examples of auxiliary verbs expressing tense

• I have been sitting here since 7 o’clock.
• Sarah was waiting for the shark to reappear.
• John will have broken the record by then.

Here are some examples of auxiliary verbs expressing voice:

• Unfortunately, our ice cream has been eaten by the cat.
• The broadband will be disconnected tomorrow.

Here are some examples of auxiliary verbs being used to express mood:

• If he should arrive, tell him to leave.
• If he were to arrive in the next 10 minutes, we would still be on track.