Thank you all !! :)) I guess I roughly understood about how to use "AS" but I'm still not sure about difference between SINCE and BECAUSE( I mean,what kind of situations should I use these in?) I googled it and according to the article I read,"BECAUSE is used when the reason is the most important part of the sentence. SINCE and AS are used when the reason is already well known and is therefore usually less important.The as or since clause is usually placed at the beginning of the sentence. " Do natives actually use these conjuctions in this way?
@hk0905 "Since" can be used as 1. pertaining to what has been happening in the past that continues at the present. For example: Since birth, my mother is always at my side. 2. describing a fact that happened/that is happening/that will happen, and you use that fact to justify your statement. For example: Since I have a job now (this is the fact), I can buy whatever I want (this is your statement).
"As" can be used 1. for comparison. For example: She has a skin as white as snow. 2. to quote a statement according to someone/something. For example: As the golden rule says, "Do unto others what you want others do unto you." 3. to describe the starting point of something. For example: As you put your money in a bank (starting point), it will earn interest (something).
"Because" is solely pointing out the reason why something happened. For example: Because you were late, we were not able to catch the train on time.