单选题 All the staff members of the department made concerted efforts to ______ the hall for the Christmas party.
A. clean up B. clear up C. dress up D. make up

【正确答案】 A
【答案解析】[解析] clean up“彻底清扫”；clear up“天晴起来”；dress up“打扮起来”；make up“化妆”。从句子意思上看，只能选clean up。