You should do more instead of sitting at the desk busy doing your .A. exercise; exercises

问题补充：

You should do more instead of sitting at the desk busy doing your .

A. exercise; exercisesB. exercises; exerciseC. exercise; exercise

答案：

解析：句意：你应该做更多的锻炼来取代坐在课桌前忙于做练习题。分析：考查单词exercise作为名词，译为“锻炼”时为不可数名词，但是译为“练习”时为可数名词。因此前句为锻炼，因此用动词的原形；后者为练习，为可数名词，因此用名词复数形式。故选A