In the question, “Could the alarm have failed to ring?” the verb phrase is “failed to ring.”
<u>Explanation:</u>
A certain portion of a statement which consists of an object, direct or indirect and a verb. It bridges the subject of the verb with the information that the subject is offering, then it serves the purpose of a verb phrase. It can be the predicate of a sentence or a certain clause. It can also operate as an adverb or adjective, and at the same time comprise of a verb and its objects, modifiers and other segments.
