【题目】To keep healthy, Professor Johnson ______ cycling as a regular form of exercise after he retired.
A. carried out B. caught on C. took up D. made for
在线课程【答案】C
【解析】
试题分析：考查动词短语。在退休后，为保持健康，约翰逊教授开始把骑自行车作为一项固定的锻炼方式。carry out开展； catch on变得流行； take up开始从事； make for导致，有助于。故选C。