问题补充：
Taking exercise and eating food can make you keep thin.
A. more; less
B. more; fewer
C. less; more
D. fewer; less
答案：
(答案→)A. more; less
B. more; fewer
C. less; more
D. fewer; less
解析：句意：做更多的练习，并且吃更少的食物能够使你保持瘦。exercise不可数名词，用more即much的比较级修饰；food不可数名词，用less即little的比较级修饰。故选A.
