21. In communication, a smile is usually _____ strong sign of a friendly and _____ open attitude.
A. the; / B. a; an C. a; / D. the; an
22. More money and effort should be spent to _______ the cultural relics in the world.
A. keep B. remain C. preserve D. support
23. He had a strange hairstyle and he instantly became the ______ of attention the moment he stepped into the classroom.
A. aim B. focus C. direction D. point
