because, as, since or for

Word Explanation and Example

because : The reason is very important in the sentence, so "because"comes in the second clause of the sentence. I read this book because I like it.

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. We went to a small restaurant - for we were hungry.