Progressive tenses (also known as continuous tenses) are formed by combining a form of the auxiliary verb "be" with the present participle (which ends in -ing) of a main verb.
Here's how it works:
* Present Progressive: "am/is/are" + verb-ing (e.g., "I am walking," "She is sleeping")
* Past Progressive: "was/were" + verb-ing (e.g., "They were eating," "He was writing")
* Future Progressive: "will be" + verb-ing (e.g., "We will be traveling," "You will be working")
Any verb can be used in a progressive tense.
Therefore, there's an unlimited number of progressive verb forms, as it depends on the main verb and the tense you're using.