21. —There is a chess match between a Korean player and AlphaGo(阿尔法).
—It’s very amazing. Playing _____ chess is usually ________ one-to-one game.
A. /；a B. the; a C. /；an D. a; the
22. —Where is your father now?
—He _________ Hong Kong. He _______ there for three days.
A. has gone to; has been B. has been to; has been C. has gone to; has been to D. went; was
