D、B and C
宾语从句用陈述句语序,B对
what has happened to you 比较特殊,可以理解为已经是陈述句语序了,what视作主语
类似的有 Can you explain what's wrong with you/ what's the matter with you为什么是what has而不是what is？'s=has/is 都有啊，看具体结构需要啥She's been there before=She has been there beforeShe's sleeping=She is sleepinghappen是无被动的，所以作现在完成时的has