Answer:
The subordinating conjunctions are used to form dependent clauses. There must be a complete clause, otherwise the word may be a preposition. The common ones include words also used as pronouns (who, what, which) and also when, where, and how. Other subordinating conjunctions include:
-------One word
after
although
as
because
before
if
inasmuch (now rare)
lest (now rare)
once
since
though
unless
until ('til)
whenever
whereas
whether (or not)
while
--------Phrases
as if
as long as
as much as
as soon as
as though
by the time
even if
even though
every time
in case
in the event that
in order that
just in case
no matter (what, when, where which, who, how)
now that
only if
provided [that]
so that
the first time