Final answer:
The verbs to do, to have, and to be can function as both main and auxiliary verbs in the English language. They help form questions, negative sentences, continuous tenses, and perfect tenses depending on their use in a sentence.
Step-by-step explanation:
The verbs to do, to have, and to be are versatile in their usage in the English language. They can function as either a main verb or auxiliary verb in a sentence. For example, when to be is used as the main verb, it is followed by an adverbial of time or place, an adjectival, or a noun phrase. As an auxiliary verb, to be helps form the continuous tenses (i.e., am/is/are + present participle).
To do is used as a main verb to indicate an action taken by the subject, such as 'I do my homework.' As an auxiliary verb, it helps form questions and negative sentences, like 'Do you like ice cream?' or 'I do not like ice cream.'
To have as a main verb expresses possession, such as 'I have a car.' When used as an auxiliary verb, to have assists in creating perfect tenses, for instance, 'I have finished my work.'