英语单选题.Mr Barre doesn't think that all language should be all

英语单选题.Mr Barre doesn't think that all language should be allowed .In his opinion ,th...
英语单选题.Mr Barre doesn't think that all language should be allowed .In his opinion ,there are ()that should be kept up .选玩后翻译一下并说明选择理由.
A.degrees B.levels C.limits D.standards