You're likely thinking about the present participle being used with a helping verb to create a present progressive tense. Here's how it works:
* Present participle: This is the "-ing" form of the verb (e.g., "running," "walking," "talking").
* Helping verb: These verbs help to create different tenses and moods. The most common helping verb for present progressive tense is "be" (am, is, are, was, were).
Example:
* Present progressive tense: "He is walking to the store." ("walking" is the present participle and "is" is the helping verb)
Note: While the present participle is used to create the present progressive, it's not a separate grammatical form called the "progressive infinitive."
Let me know if you have any other questions about verb tenses!