题目

-- Mum, I failed again in today’s examination. --Oh, ________. The world is not _______. A. come up; at its end          B. Cheer up; in the end  C. Look up; at the end          D. Take it easy; at an end  答案：D一个圆的半径5厘米，如果半径增加20%后，周长增加________厘米，面积增加________%．