Words That Can Function as Prepositions

      Prepositional phrases are simply prepositions plus the noun or pronoun that answers the question "What?" after them: "in the house," "under the desk," "from the street." Thus, to identify prepositional phrases you need to recognize prepositions and then make a question with "What?" after them -- "Under what?" -- "Under the desk."

If a verb answers the question "To what," it is not a prepositional phrase.
about
above
across
according to
after
against
along
among
around
as
aside from
as for
as to
at
because of
before
behind
beneath
beside
between
beyond
but *
by
despite
down
down to
due to
during
except
for
from
Words That Can Function as Prepositions
Note: Some prepositions consist of more than one word.

Note that 
all the words 
in brown
could be used
to tell a squirrel's relationship 
in space 
to trees:

 

The squirrel is ____ the trees.

Other prepositions express 
relationships in time:

They left after dinner.
They arrived before dinner.
We talked during dinner.
We haven't eaten since dinner.
We waited until dinner.

The word that answers the question "What?" after a preposition is called the "object of the preposition."

in
inside
instead of
into
like
near
of
off
on
onto
opposite
out
out of
outside
over
per
regardless of
since
such as
than
through
to
toward
under
until
up
upon
via
with
within
without
* when it means "except"