required set

例句：

1. 1.The teacher required us to finish the homework before class.
   老师要求我们在上课前完成作业。
2. 2.The meeting was called because there were some requirements that needed to be met.
   会议被召集是因为有一些要求需要满足。
3. 3.The new policy requires all employees to wear a safety helmet when working on site.
   新的政策要求所有员工在工作现场时必须佩戴安全头盔。