Here's why:
* Pronouns indicate who or what is doing or being something. They don't show when the action happened.
* Tense is shown by verbs. For example, "I *walked*" is in the past tense, while "I *walk*" is in the present tense.
Examples:
* Past tense: "He *went* to the store."
* Present tense: "He *goes* to the store."
In both sentences, the pronoun "he" remains the same, but the verb changes to indicate the tense.
Let me know if you have any other questions about pronouns or verb tenses!