（智力的）运用；（尤指）锻炼运动时不可数,比如说：The doctor advised him to take more exercise.(发音,体操,保健,深呼吸,钢琴等)练习,训练时可数,比如说：The teacher set her class a mathematics exercise for homework.还有（部队等的）操练,演习也是可数的,比如说：military exercises军事操练