Coordinating conjunctions connecting clauses: I stopped, for I was not sure. (for joins the clauses I stopped and I was not sure.) Sam loves classical music, but his brother doesn't (but joins the clauses Sam loves classical music and his brother doesn't. We can go to the concert, or we can stay home. (or joins the clauses We can go to the concert and we can stay home. It should be remembered that a coordinator should be preceded by a comma when used to connect two independent clauses as shown in the above examples.