Here's why:
* Action verbs: Describe actions, like "run," "jump," "eat," "write."
* State of being verbs: Describe a state of existence or condition, like "is," "are," "was," "were," "seems," "feels."
The principal parts of a verb are the base forms used to create different tenses and forms of the verb. They are:
1. Infinitive: The basic form of the verb, usually preceded by "to" (e.g., "to run," "to be").
2. Past Tense: Describes an action that happened in the past (e.g., "ran," "was").
3. Past Participle: Used to form perfect tenses (e.g., "run," "been") and sometimes passive voice (e.g., "run," "been").
4. Present Participle: Ends in "-ing" and is used to form progressive tenses (e.g., "running," "being").
Therefore, the principal parts of words are directly related to verbs and their ability to express action or states of being.