Take the tour ×  Put the book back on the table.  I'm having
trouble. I think it is a preposition.  share|improve this
question add comment  4 Answers  It serves the function of
controlling/modifying the verb put, so it is an adverb.  A
preposition is a part of speech used to connect a noun or
pronoun. Back is obviously not used in this way here. The only
preposition here is on, as it connects the noun phrase the
table.  share|improve this answer add comment  First, and most
important, asking what part of speech a particular word is tells
you nothing about it, or about grammar, or about English.
Nothing. Even if you get an answer. It's the wrong question.
Second, put back is a Phrasal Verb, and the back part is
generally called a "particle". (See what I mean about telling
you nothing?) The put part is called the "verb", which is also
not terribly useful.  Phrasal verbs consist of a "verb" plus a
"particle", which usually has the same form as a preposition,
but doesn't have an object. Some linguists call it a