To introduce the cause, we can use because, because of, due to, since or as.

• If this clause is at the beginning of the sentence, use a comma afterwards.

FOR EXAMPLE:

Since they’re going on holiday tomorrow, they’re delighted.

• If this clause is at the end of the sentence, there is no comma.

FOR EXAMPLE:

They’re delighted because they’re going on holiday tomorrow.

To introduce the effect, we can use as a result, for this reason, or so.