mandatory attribute

例句：

1. 1.The government has imposed a ban on the sale of tobacco products in public places.
   政府已经禁止在公共场所销售烟草产品。
2. 2. This law is mandatory for all employees working in the company.
   这项法律对所有在公司工作的雇员都是强制性的。
3. 3. The teacher required all students to complete their homework before class.
   老师要求所有学生在上课前完成作业。