obligatory [əˈblɪgətɔ:ri]

例句:

• His lips curved up in the obligatory smile, acknowledging the compliment.
  他嘴边礼节性地挤出一个微笑，以示对称赞致谢。
  
• There was all the usual humbug and obligatory compliments from ministers.
  全都是些部长们常说的骗人鬼话和少不了的奉承恭维。
  
• She was wearing the obligatory sweater and pearl necklace.
  她穿着那件经常穿的毛衣，戴着那串惯常戴的珍珠项链。
  
• Zakaah is an obligatory form of charity on savings.
  来自SA
• But he argues minarets are not obligatory in Islam.
  来自VOA
• When I have company I consider it obligatory.
  来自WSJ