Here's why:
* Helping verbs assist the main verb in a sentence to express a specific tense, mood, or voice.
* Linking verbs connect the subject of a sentence to a noun or adjective that renames or describes it.
"Can" doesn't connect the subject to a description; it helps the main verb express ability or possibility.
Examples:
* I can swim. ("Can" helps the main verb "swim" express ability.)
* She can go to the party. ("Can" helps the main verb "go" express possibility.)
Let me know if you have any other questions!