What are auxiliary verbs

**Auxiliary verbs**, also known as helping verbs, are verbs used alongside a main verb to express various grammatical functions such as tense, mood, voice, or aspect. They help form different verb tenses and structures. 

Common auxiliary verbs include:

1. **Forms of "be"**: Used to form continuous (progressive) tenses and passive voice (e.g., "is running," "was built").

2. **Forms of "have"**: Used to form perfect tenses (e.g., "has eaten," "had gone").

3. **Forms of "do"**: Used to form questions, negatives, and emphatic statements (e.g., "Do you like it?" "She does not understand," "I do like it").

Auxiliary verbs are essential for constructing complex verb phrases and providing additional information about the action or state described by the main verb.