Adverb 'as'
1.To the same degree
"birds were singing and the child sang as sweetly"; "sang as sweetly as a nightingale"; "he is every bit as mean as she is"
2.In the idea, character, or condition of, limiting the view to certain attributes or relations
"dressed up as a ghost"
Conjunction
1.At the same time that
"they were walking home as they were discussing the problem"
2.For the reason that; on account of
"empty, as it had been upside down"
while Preposition "since"
1.From that time
"happy since getting married"
Conjuction
1.For the reason that; on account of
"Since it's snowy, let's go skiing"
cowboy...