一、基础用法

1. The company organized a variety of activities to celebrate the anniversary.（公司组织了多种活动庆祝周年纪念日。）

2. She enjoys outdoor activities like hiking and cycling.（她喜欢徒步和骑自行车等户外活动。）

二、行为活动描述

1. The teacher encouraged students to participate in class discussions as part of the learning activity.（老师鼓励学生作为学习活动的一部分参与课堂讨论。）

2. The experiment involved recording the electrical activity of the brain.（实验包括记录脑电活动。）

三、抽象活动表达

1. Reading books is a great way to enrich your inner activity.（阅读是丰富内心活动的绝佳方式。）

2. The conference provided a platform for professional activity.（会议为专业活动提供了平台。）

四、固定搭配

1. Keep active: Regular exercise is key to good health.（保持活跃：规律锻炼是保持健康的关键。）

2. Set in motion: The new policy will set the company's activities into motion.（付诸行动：新政策将推动公司活动的开展。）

五、特殊场景

1. The charity event raised a lot of awareness about environmental activity.（慈善活动提高了人们对环境活动的认识。）

2. The festival activities included traditional games and cultural performances.（节日活动包括传统游戏和文化表演。）

注：部分句子中"activity"的释义可能根据上下文有所调整，例如"mental activity"（心理活动）等。建议结合具体语境选择合适表达。