21. ---Excuse me, what can I do for you?
---Yes. I'd like to place ________ advertisement for ________ used car in your paper.
A. the; a B. an; / C. an; a D. /; the
22. ---I'm trying to find yesterday's newspaper. Have you seen it?
---I'm afraid that I ________ it away. I thought you had finished reading it.
A. threw B. had thrown C. throw D. will throw
