obligatory
adj. 有义务的，强制性的；惯常的，赶时髦的；（规定，裁决）有约束力的
例句
Priority must be given to the development of obligatory activities.
必须优先发展义务活动。
In the mid 60s he took the almost obligatory trip to India.
六十年代中期，他也赶时髦到印度一游。
《牛津词典》
It is obligatory for all employees to wear protective clothing.
所有员工必须穿防护服装。
