1、作可数名词用,“练习,习题,体操,功课,操练”等,常用复数。

I'm doing my exercises我在做练习/功课。

Doing morning exercises is helpful to our health做早操对我们的健康是有益的。

You should do more spelling exercises你应该做更多的拼写练习。

2、作不可数名词用,“锻炼,运动”。

You are weak because of the lack of exercise你身体弱是因为缺少锻炼。

Take more exercise,and you will be healthy多多锻炼,你会健康的。

3、作动词用,“训练,锻炼”。

You must exercise yourself in order to be stronger and healthier为了更健康更强壮,你必须锻炼自己。

They are exercising troops他们在练兵。

You don't exercise enough你锻炼不够﹝作不及物动词﹞。