Question

Mr. Smith took interest in ____ he had seen in the history museum.A all what B all which C what

D that 请问这题目选什么？为什么？

Answer 1

C
宾语从句
把what he had seen in the history museum 作为宾语——他在历史博物馆看到的东西。

追问

请问前面为什么不能加all？

追答

没有这种用法
你可以填all that表示他在历史博物馆看到的所有东西，此时that是关联词，构成定语从句，he had seen in the history museum修饰all。all是不定代词，定语从句中只能用that作关联词，所以B也不对。但是没有all that这个选项。