Although Standard English allows some linking verbs and helping verbs to be contracted in informal contexts, it does not allow them to be omitted.

Linking verbs, used to link subjects to subject complements, are frequently a form of be: be, am, is, are, was, were, being, been. (See 47b.) Some of these forms may be contracted (I’m, she’s, we’re, you’re, they’re), but they should not be omitted altogether.

Helping verbs, used with main verbs, include forms of be, do, and have and the modal verbs can, will, shall, could, would, should, may, might, and must. (See 46c.) Some helping verbs may be contracted (he’s leaving, we’ll celebrate, they’ve been told), but they should not be omitted altogether.