Answer:
Subject:The dog.
Action verb:Happy.
Linking verb:is.
Explanation: The dog is the subject in the sentence because it is the doer of the action while happy is the action verb because it is telling us how the dog is feeling it is showing the dog's action or reaction in the sentence and "is" is a linking verb because it is linking the other words together but am not so sure that's the answer because a linking verb is considered a conjunction because it joins two words or sentences together and also I don't think there is any adjective in the sentence if happy is considered an adjective then it is supposed to be "happily" not "happy" ,and the object can be "street" because it is the 2nd thing in the sentence that the doer of the action is referring to or acting on..... Thank you...I hope I answered the questions and if u find another answers to your question then please inform me because I would love to know the answers. Thanks