appropriacy       
noun [ U ] uk/əˈprəʊ.pri.ə.si/ us/əˈproʊ.pri.ə.si/
 language specialized(措词的)准确性;得体性 
the fact that a word or phrase sounds natural and is acceptable when used in a particular situation 
  Teachers aim to assess the appropriacy of the language used by their students in particular contexts. 老师们旨在评估学生在特定语境中使用语言的得体性。