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Practical English Usage
as,because,since and for
All four of these Words can be used to refer to the reason for something.They are not used in the same way.
1.as and since
They used when the reason is already known to the listener/reader,or when it is not the most important part of the sentence.They often come at the beginning of sentences.
-As it's raining again,we'llhave to stay at home.
-Since he had notpaid his bill,his electricity was cut off.
2.because
Because puts more emphesis on the reason,and most often introduces new information which is not known to the listener/reader.
-Because I was ill for six months,I lost my job.
When the reason is the most important part of the sentence,the because clause usually comes at the end.It can also stand alone.Since and as can not be used like this.
-Why am I leaving?I'm leaving because I'm fed up.
3.for
For introduces new information,but suggests that the reason is given as an afterthought.It never com at the beginning of sentences,and can not stand alone.
-I decided to stop and have lunch_for I was feeling hungry.
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