Final answer:
Helping verbs, also known as auxiliary verbs, assist main verbs in forming verb phrases to express various tenses, aspects, moods, voices, and conditions.
Step-by-step explanation:
The subject of this question is English. Helping verbs, also known as auxiliary verbs, are used in combination with main verbs to express various verb tenses, aspects, moods, voices, and conditions. They assist the main verbs in forming verb phrases. For example, in the sentence 'I could finish my essay by eight o'clock tonight,' the verb 'finished' is attended by the auxiliary 'could,' which indicates the ability or possibility of completing the action.