Yes , it is the present participle form of the verb yawn yawn yawns yawned yawning
yawning
voluntary
It is an action verb.
began is an action verb, not a linking verb.
"Sent" is an action verb. It shows an action, such as "she sent an email."
what follows a linking or action verb
It is an action verb.
action verb
Action verb
Action verb
An action verb