act of courtesy

例句：

1. 1.When he arrived at the airport, he gave a polite smile and greeted everyone.
   当他到达机场时，他给了大家一个礼貌的微笑并问候了每个人。
2. 2.She offered to help him carry his heavy suitcase, showing her act of courtesy.
   她主动提出帮助他搬运沉重的手提箱，展现了她的礼貌举动。
3. 3. The teacher's thoughtful act of courtesy made the students feel valued and appreciated.
   老师的体贴行为让学生们感到被重视和感激。