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SERIES

Place a comma before the and or or that introduces the last member in a series of three or more items. When the last item consists of two or more items, two ands are generally needed. Separate the items in a series with semicolons when they are complex and include interior punctuation.

            pepper, millet, and gold
             coffee, tea, and bottled beer and ale
             We arrived; ate, for we had missed lunch; and, after a long conversation, went to bed.