区别就在于意思：
1.exercise泛指“锻炼”时,做不可数名词,如：take exercise 锻炼身体 take more exercise多锻炼，泛指“锻炼”并不是指定某一种锻炼的方式，锻炼的方式有很多种，是数不清的，所以不可数。
2.exercise表示“体操”或“练习（题）”时是可数名词,要用复数形式.如： do morning exercises（做早操）,do eye exercises(做眼保健操),do English exercises(做英语练习)，特指某一种东西或者方式时就是可数的。但是有一种特殊情况，与知识学习有关的练习是可数名词,有单复数之分.动词搭配用do.比如：Today,I'll give three exercises to do.
exercise表示可数造句：
1.We do English exercises to help us learn good English. 我们做英文练习以便学好英语。
2.Do Exercises 3 and 4 on page 51 for homework. 家庭作业做51页的练习3和练习4。
3.Relaxation exercises can free your body of tension. 放松运动可以松缓身体的紧张。
4.The instructor does exercises that you can copy while you watch. 教练做操时你可以边看边模仿。
5.We do morning exercises every day. 我们每天做早操。
6.Will you attend the graduation exercises? 你将出席毕业典礼吗？
7.We do eye exercises during the break.我们休息时做眼保健操。
8.You can do exercises to strengthen your stomach muscles.你可以锻炼你的腹部肌肉。
exercise表示不可数造句：
1.Exercise was part of their daily ritual. 锻炼是他们日常习惯的一部分。
2.Diets are most effective when combined with exercise. 节食和锻炼相结合是最有效的。
3.I do exercise every day。我每天都做运动。
4.Doing more exercise is helpful to our health。多做运动对我们的健康有益。
5.You've put on weight!Better take exercise every day.你体重增加了！最好每天锻炼。
6.Most people need to do more exercise.大多数人需要更多的锻炼。
