1) ACTUAL FACT / ACTUALLY
“In actual fact” is an unnecessarily complicated way of saying “actually.”
2) ADD / AD
Advertisement” is abbreviated “ad,” not “add.”
You can adopt a child or a custom or a law; in all of these cases you are making the object of the adoption your own, accepting it. If you adapt something, however, you are changing it.
You can minister to someone by administering first aid. Note how the “ad” in “administer’resembles “aid” in order to remember the correct form of the latter phrase. “Minister” as a verb always requires “to” following it.
5) ADULTRY / ADULTERY
“Adultery” is often misspelled “adultry,” as if it were something every adult should try. This spelling error is likely to get you snickered at. The term does not refer to all sorts of illicit sex: at least one of the partners involved has to be married for the relationship to be adulterous.