Frank Nelson, M.D., will speak at the banquet. Use a comma to contrast elements in a sentence. I met George, not John. She is a lawyer, not a doctor. Use a comma to separate an independent clause from a question dependent on the clause.
Introduction Use a comma after an introductory yes or no .
Yes, I was there. After an introductory phrase, use a comma. On turning the corner, George ran into Miss Ware. To get a ticket, we had to threaten the people in front of us. Use a comma after an introductory clause.