Question

select the two prepositional phrases. a mobile composed of shimmering mirrors and silver wire swayed gently in the elegant hotel lobby.

Explanation:

A prepositional phrase starts with a preposition and ends with a noun or pronoun. "composed of" is a phrasal preposition and "in" is a preposition. So "composed of shimmering mirrors and silver wire" and "in the elegant hotel lobby" are prepositional phrases.

Answer:

"composed of shimmering mirrors and silver wire", "in the elegant hotel lobby"