Question

【题目】If you want to keep healthy, you should________ some exercise every day.

A. to do B. doing C. did D. do

Answer 1

【答案】D

【解析】

句意：如果你想要保持健康，你应该每天做一些锻炼。to do动词不定式；doing动名词；did是do的过去式；do做，动词原形。空前的should是情态动词，后面跟动词原形，故应选D。