Q: Years (and years!) ago when I learned grammar and usage from the Sisters of St. Joseph in a Brooklyn, N.Y., grammar school, a series of nouns used a comma to separate the nouns until the last one, ...

Before I started teaching copy-editing courses, I assumed that one of the nice things about being a teacher would be sharing hard-earned expertise with wide-eyed students awed by my vast knowledge.

While we all slip up from time to time, there are some basic punctuation mistakes you should never make in formal writing. For example, don't confuse "it's" and "its," don't use an apostrophe to ...