Curated OER
To Be or Not To Be - Main/Helping Verbs
Fourth graders focus on the use of main and helping verbs in written communication.
University College London
University College London: Auxiliary Verbs
This site has information on auxiliary verbs. Includes a short exercise to test your knowledge.
English Club
English Club: Learn English: Grammar: Verbs: Forms of Main Verbs
Explanations and examples of different verb forms including main verbs, infinitives, and various tenses.