英语词汇学问题 what are the characteristics of English phrasal verbs

A Phrasal Verb is an English verb which is composed of two or three words.One
verb is combined with a preposition (like on,in,under) or an adverb (like up,
down,away).Sometimes a phrasal verb can have a meaning that is very different
to the meaning of at least one of those two or three words separately.Phrasal
verbs are used more frequently in everyday speech than in formal,official
writing or speaking.