Editor's Note: APYs listed in this article are up-to-date as of the time of publication. They may fluctuate (up or down) as the Fed rate changes. CNBC Select will update as changes are made public.

They can be used to join together two clauses in a sentence. However, the clauses need to make sense on their own. For example: I had a terrible cold. I still went to work. You can add the ...