"was stolen" is a Verb.
Parts of speech (nouns, pronouns, verbs, adjectives, adverbs, prepositions, conjunctions, and interjections) are categories in which a word falls. More than one word doesn't have a specific part of speech.Had + stolen creates the past perfect tense. Had is an auxiliary verb, stolen is the past participle of the verb steal.
In the sentence "The stolen car was recovered." it is an adjective. In the sentence "He has stolen two cars." it is a verb.
part of speech
The part of speech for this particular word is a noun.
The part of speech for "answer" is a noun.
adverb
what part of speech is beneath
The part of speech for "explicit" is an adjective.
The part of speech for "twirl" is a verb.
The part of speech for "unfamiliar" is an adjective.
The part of speech of "came" is a verb.
The part of speech for "lecturer" is a noun.