Definition: If something is compulsory, you must do it because of a rule or law. Level: B2
法律规定在车内系安全带是强制性的。
Wearing seat belts in cars is ___compulsory by law.
游泳在我学校是必修的。
Swimming was ___compulsory at my school.
活动中穿传统服装不是强制性的。
Wearing traditional dress is not ___compulsory for the event.
