0 If something is obligatory, you must do it because of a rule or law, etc. -- （根據規定、法律等）必須履行的，強制性的，有義務的
The medical examination before you start work is obligatory. 工作前必須先體檢。
[ + to infinitive ] The statute made it obligatory for all healthy males between 14 and 60 to work. 這條法令規定所有年齡在14至60歲的男子必須工作。
Several Secret Service agents surrounded the President, all wearing the obligatory raincoat and hat. 幾名特工圍在總統四周，當然是一律穿著風雨衣，戴著帽子。
The underlying dynamics of sibling relationships have been identified as balanced reciprocity, optional rather than obligatory exchange of support and the maintenance of personal autonomy.
To suppose that all formally valid laws are morally obligatory is a moral error.
Partial effects can be interpreted in terms of mutual (de)stabilization rather than obligatory inclusion.
Under most circumstances, few would expect an obligatory relationship between the activation of some eccentric retinal ganglion cells and the initiation of an eye movement.
The language exhibits obligatory subject-verb agreement, two pronominal genders (animate and inanimate), and morphologically marked tense-aspect, postpositions, definitization, and pluralization.
He was in favor of obligatory instruction for children because he feared that otherwise parents would exploit them.
Quite obviously though, this is not an explanation ; the question was, why is coreference obligatory in these constructions.
Take is usually a transitive verb, yet although it has an obligatory direct-object argument, locative arguments are normally optional.
