1. be (am, is, are, was, were, been, being)
2. seem
3. appear
4. become
5. feel
These verbs don't show an action; instead, they connect the subject of a sentence to a word or phrase that describes or identifies the subject.
Examples:
* The sky is blue. ("Is" connects "sky" to the description "blue")
* She seems happy. ("Seems" connects "she" to the description "happy")
* The cake appears delicious. ("Appears" connects "cake" to the description "delicious")
* He became a doctor. ("Became" connects "he" to the identity "doctor")
* I feel tired. ("Feel" connects "I" to the description "tired")