Yes, occurred, the past tense of occur, is a verb.
A verb is a word that describes an action (run, walk, etc), a state of being (exist, stand, etc) or occurrence (happen, become, etc).
Occurred is the past tense conjugation of the verb occur.
Generalization
That is the correct spelling of "occurrence" (an event).
occurred
That is the correct spelling of "recurred" (occurred again).
THE PAST Participle of occur is occurred!
The main verb in the sentence is "occurred".
"Has/have occurred" is the present perfect tense. "Already" is an adverb.
Was already is a verb. Was is the singular past tense be verb.
"were" is a 'to be' verb
Yes, "were destroyed" is a verb phrase that functions as the verb in a sentence. It is in the past tense and indicates an action that occurred.
WERE is a verb like for example you were we were
The verb forms are occur, occurs, occurring, and occurred. The noun forms are occurrence and occurrences.
Yes, "slipped" is a past tense verb form of the verb "slip". It indicates an action that occurred in the past.
"Walked" is the past tense form of the verb "walk," which is a regular verb. It describes an action that has already occurred. In grammatical terms, it functions as a transitive or intransitive verb, depending on the context in which it is used.
Event is the subject and occurred is the verb
Occurred is the past tense conjugation of the verb occur.