In using a colon to introduce a quotation, be sure the clause before the colon is a complete sentence (can stand alone). which sentence below uses a colon correctly? a. my teacher's favorite shakespeare quote is: "to be or not to be -- that is the question." b. my teacher is always quoting shakespeare when he says: "to be or not to be - that is the question." c. my teacher is always quoting shakespeare: "to be or not to be -- that is the question."