because, as, since or for
When do we use because, as, since and for?
|because||The reason is very important in the sentence.||The students could go home earlier because the teacher was ill.
Because the teacher was ill, the students could go home earlier.
|as||The reason is already known.||As we read, we learn.|
|since||The reason is already known. (more formal than as)||Since we were in the computer lab, our English has improved.|
|for||The reason is given at the end of the sentence.
The clause with for cannot be used in inital position.
|We went to a small restaurant - for we were hungry.|