Question

(   ) 1. You should do more       Don't always sit at desk busy doing your .

A. exercise, exercise B. exercise, exercises  

C. exercises, exercises    D. exercises, exercise

Answer 1

1. B do exercise意为"锻炼，运动"，其中的exercise为不可数名词；do one's exercises意为"做练习，做作业"，此处的exercise为可数名词。