3. subordinating conjunctions

a. introduction (general / mixed) 
b. subordinating conjunctions for different purposes 

e.g.: though, besides, in addition to, rather than, because, since, now that, as, in order, as long as, inasmuch, because of, due to, owing to, so that, in order that, if only because, as if, as though, if, only if, unless, even if, whether, whether or not, provided (that), in case, in the event (that), although, even though, though, while, whereas, despite, in spite of, regardless of, where, wherever, after, before, when, while, since, as, until, as soon as, by the time, once