To keep healthy Mr. Smith cycling as a regular form of exercise after he retired.A. took

问题补充：

To keep healthy, Mr. Smith cycling as a regular form of exercise after he retired.

A. took up

B. put up

C. gave up

D. made up

答案：

(答案→)A. took up

B. put up

C. gave up

D. made up

解析：短语辨析。A占据，从事于，开始做；B张贴，搭建了；留宿；C放弃；D化妆，编造，弥补；组成；句意：为了保持健康，斯密斯先生退休以后开始把骑自行车作为一种锻炼的方式。根据句意说明A正确。