morning. In our English lit class, is not acceptable. Or would you prefer "and so on "and so forth" or something similar? At the end of "etc there should be a period. If it is in parentheses in the middle of a sentence or at the end of a sentence, no comma is needed. You may or may not have used it in your own assignment writing, but chances are you may not be using it correctly. Items of the same class do not need to be physical items. She will have to sit when he sits, kneel when he kneels, et cetera, et cetera, et cetera.
If you only need cookies, cake, and donuts for the party, writing "cookies, cake, donuts, etc." will not be appropriate because it will give the reader the assumption that he can bring another dessert. S in speaking or in informal writing is often used for emphasis, using etc. This kind of mispronunciation is called assimilation. It is a mistake, but a very common one. Warnings While the rule is not always observed, et cetera is usually used for things.