What's at the Bottom of the Growing Rift Between South Korea and the US?
美韩之间愈演愈烈的分歧到底是什么?
据我所知“What's at the Bottom of ……”表示……究竟是什么?（或者究竟怎么样了?）并不常用.
常用的有：
what on earth are you doing?你究竟在干什么?
what the hell are you doing?你究竟在干什么?
what in the world are you doing?你究竟在干什么?