他每天晚饭后散步半小时作为锻炼。

He goes for a 30-minute walk after dinner as his daily ___exercise.

法官正在行使他的权力作出最终判决。

The judge is ___exercising his power to make the final decision.

老师让学生们通过解题来练习数学技能。

The teacher has students ___practice their math skills by solving problems.