An adverbial phrase usually consists of two or more words: an adverb being the head word in an adverbial phrase plus other words, although it can consist of only one adverb. The adverbial phrase functions as an adverb in a sentence, and is often a prepositional phrase that modifies a verb, adjective, or adverb.
- He ate his ice cream in a train.
(The adverbial phrase in a train modifies the verb ate.)
- She seems happy with her puppies.
(The adverbial phrase with her puppies modifies the adjective happy.)
- Bob hates to wake up early on Monday morning.
(The adverbial phrase on Monday morning modifies the adverb early.)