This document discusses multi-word verbs in English grammar, specifically phrasal verbs and prepositional verbs. It notes that multi-word verbs can fall into four categories: phrasal verbs, phrasal-prepositional verbs, prepositional verbs, and other constructions. A key difference explained is that prepositional verbs behave like a single lexical unit where the meaning can be understood from the individual parts, unlike phrasal verbs where the meaning is idiomatic. The document analyzes the morphological, semantic, syntactic and phonological differences between the examples "look up" and "look at" to illustrate how phrasal verbs and prepositional verbs differ.