Auxiliary verb
A helping verb used with a main verb to form compound verb phrases expressing tense, aspect, mood, and voice. Auxiliary verbs include be, have, do, and modals.
Real World
BBC News headlines often drop auxiliary verbs ('PM to visit Brussels' instead of 'PM is to visit Brussels') to save space, which also creates a more immediate, punchy tone for readers.
Exam Focus
Always state which grammatical function the auxiliary performs — tense, aspect, voice, or emphasis — not just that it 'helps' the main verb.
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