Question

哪位老师帮忙解释一下面这道题吧，尽量详细一点，谢谢

_____ is known to us all is that the old scientist, for______ life was hard in the past, still works very hard in his eighties.( )
A. As；whom B.What；whom C. It；whom D.What；whose
答案是B

Answer 1

首先可以排除D，因为后面for（介词）后面要接宾格，应该填whom
再来看前一句，正常语序应该是：the old scientist is known to us all.
——is known to us all is that the old scientist这个句子前半部分缺少主语，所以要用what.
waht引导的是一个主语从句

假如要用it，那么应该是It is known to us all that the old scientist【all 后面的is不能要】
it作形式主语，真正的主语是后面的the old scientis was hard in the past
假若要用as的话，as引导非限制性定语从句，前面应是as is known to us，+一个完整的句子。

Answer 2

what is known to us all 主语从句。for whom ....past 是定语从句，在表语从句that （连词） the old scientist still works very hard in his eighties.中，作the old scientist 的定语。

Answer 3

主语重句是What is known to us all ，我们都知道的是，谓语部分是系动词is，带个表语从句。表语从句中的意义是，对那个老科学家来说，过去的生活很艰苦。对。。。来说，for介词，后面接宾语，宾语又是非限制性定语从句，表人的宾格只有whom，如果想选whose，所属格，那要把前面的for去掉。