Choose the correct words to fill in the following passage.
It is difficult to write rules that tell exactly when we should apologize, (41) ____ it is not difficult to learn how. If we have done something to hurt someone’s feelings, or if we have been (42) _____ or rude, we should apologize. An apology indicates that we realize we have (43) _____ a mistake, and we are sorry (44) _____ it. It is a way of expressing our regret for something. When we (45) _____, we admitted our wrongdoing, usually offer a reason for it, and (46) _____ regret.
(41)
A.and
B.for
C.but
D.so