exercise作动词：（锻炼）单三，主语是第三人称单数的时候它是谓语动词变单三加s，例：He exercises every day.exercise作名词：（练习题）作这个意思的时候是可数名词，例：He does a lot of exercises to improve his English.（锻炼；运动）作这个意思的时候是不可数名词，例：He takes exercise every day.例外：作（体操）时可以加''s''像 morning exercises 、do exercises(=do sports做运动,例外中的例外) 、eye exercises。