This document discusses different types of adverbials, which modify verb phrases and other structures. It defines adverbials as adverb phrases, prepositional phrases, noun phrases, or clauses. Adverb phrases contain an adverb as the head. Typical adverbs end in -ly or convey time/manner without -ly. Prepositional phrase adverbials use a preposition and noun phrase. Noun phrase adverbials answer the question "when." Adverbials help clarify the tense/aspect when used with modal verbs, which are otherwise ambiguous about time frames.