Read the given sentence and identify the action verbs.
Patients are waiting outside the doctor’s room.

The correct answer is: Waiting

There are two verbs in the given sentence-- 'are' and 'waiting'. While the verb 'waiting' explains the action of the noun 'patients', the only function of the verb 'are' is to help the main action verb. The verb 'are' is known as the linking verb. The verb 'waiting' is the correct action verb. To wait means to stay in one place in expectation of someone or something.