exercise不可數名詞的用法：
（身體或腦力的）活動，鍛煉，運動：
（1）Swimming is good exercise.
游泳是有益的運動。
（2）I don't get much exercise sitting in the office all day.
我整天坐在辦公室很少運動。
（3）The mind needs exercise as well as the body.
大腦同身體一樣需要鍛煉。
行使；運用；使用：
（1）the exercise of power by the government
政府權力的行使
（2）the exercise of discretion
自行決定權的行使