Which John Smith does Graham Turner think he is talking to 讲解

Which John Smith does Graham Turner think he is talking to 讲解

主语是Graham Turner，谓语动词是think（想）.
如果是陈述句，结构是：Graham Turner thinks ... .
变为一般疑问句：Does Graham Turner think ... ?
变为特殊疑问句：疑问词+Does Graham Turner think ... ?

he is talking to which John Smith 是 一个宾语从句，整个句子作为think（想）的宾语，而which John Smith是疑问词，按句子结构的规定，要把它提到句子的前头，所以整个句子就成了：
Which John Smith does Graham Turner think he is talking to？
Graham Turner 想同哪一位John Smith交谈呢？（看来不止一个John Smith）
is talking 本来是现在进行时，这里是表示不久将要发生的行为.