Sir, <br/><br/>"Since" ia used as "preposition","conjuction" and also as adverb. <br/><br/><br/>I know its usage as preposition .........since 1990. <br/><br/>as conjuction ...............since he graduated. <br/><br/>I have no idea how to use as adverb ,Would you please expalin it? <br/><br/><br/>Thanks.