There are about 180 prepositions in the English language and the nymber of common used is not a small one. Such prepositions as of, to and in they are among top ten words that are commonly used in English. Since the main function of preposition is to combine with a noun phrase in order to form a phrase which expresses a modification, there is a lot of them. Here is list of words I find to be used as prepositions :
above
across
after
at
before
behind
below
beside
between
by
during
except
for
from
in
into
like
of
on
over
through
to
toward
under
until
up
upon
with
without
And you can see 6 extra words from the list.