It can be an adverb when used alone to modify a verb, e.g. "He smiled as he walked past." However, this is usually because there is an omitted object (past me, past us).
If used with an object, past is a preposition, e.g. "The mourners filed past the coffin." or "The inmate ran past the guards and escaped." or "it was two minutes past midnight."
The word "past" can indeed be used as an adverb. For example, in the sentence "the troops marched past", the word past is an adverb - it describes in what way the verb is completed. However, it may also be a preposition when used with an object, e.g "the troops marched past the building." In other usages, it is can be an adjective or a noun.
No: "were" is a verb, a past tense form of to be.
Like this: I did my history homework yesterday. That's how you use yesterday as an adverb in a sentence
You use the past tense form which is 'had'.
Is can be used in the past tense if it's in its past tense form, which is was.
No, it is not. Peered is the past tense and past participle of the verb (to peer) and its use as an adjective is extremely limited.
No, it is not an adverb. Reigned is a past tense verb (and past participle) that can be used as an adjective. There is no adverb form.
No, it is not an adverb. Reached is a verb, the past tense and past participle of "to reach." There is no regular adverb form.
No, it is not an adverb. The word grabbed is a past tense verb, and a past participle. The adjective "grabby" does not have an adverb form.
No. Insisted is the past tense and past participle of the verb (to insist). One adverb form is the adverb insistently.
No, it is not an adverb. The word wrapped is a past tense verb (and past participle) and can be used as an adjective. There is no adverb form.
No, it is not an adverb. Claimed is the past tense and past participle of the verb "to claim."
No, it is not an adverb. Slipped is a past tense verb and past participle (previously slipt).
Plunged is a past participle or the simple past tense. "The door plunged into the water." A past participle can be used as a noun or adverb. "The plunged door remained on the bottom of the lake." In that case plunged is used as an adjective. It modifies the noun door which makes it an adjective. Theoretically it is possible to use it as an adverb. Then it would modify a verb, an adjective, or an adverb. I have no idea how to do it.
No, "talked" is not an adverb. It is a verb, specifically the past tense of "talk." Adverbs typically modify verbs, adjectives, or other adverbs to provide more information about how an action is performed.
No, it is not an adverb. Vetoed is the past tense verb or past participle. It may be used as an adjective.
No. Barked is a past tense verb, not an adverb.