Question

请问这道改错题错在哪里？为什么？

The famous scientist, in his honor a dinner party will be held tonight, is to arrive soon.
答案写到 这是一个定语从句 所以 his 换成 whose，但是引导定语从句我记得应该是做主语吧，放在句子的最开头吧。比如 Mary want to talk to his student whose homework hasn't handed in. 这句话很明显就可以看出whose homework是做定语从句做主语。

Answer 1

在"The famous scientist,in whose honor a dinner party will be held tonight, is to arrive soon.”中, "in whose honor a dinner party will be held tonight" 是非限定性定语从句，主要是对前面的先行词the famous scientist 进行补充说明。is 是整句话的真正谓语动词。若前面用his， in his honor a dinner party will be held tonight是一个独立的句子，既没有连词也没有关系词，放在整个大句子中就不和谐了。
在定语从句中关系代词whose所修饰的词并不一定作主语。
如在下面这个句子里：This is George, whose class you will be taking. whose class 并不是从句的主语，而是宾语。

Answer 2

句子主干是The scientist is to arrive soon.中间的句子是个插入语 属于非限定性定语从句 起补充说明的作用 往往用逗号与主句隔开 想了解的更细可以看看这方面的语法书~

Answer 3

in whose honor a dinner party will be held tonight是插入语