is known to us all is that the old scientist, for life was hard in the past,still works ve

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; whose
D. As; whose

A. As; whom(答案→)B. What; whom C. It; whoseD. As; whose解析：本题考查连接代词。 is known to us all 是主语从句，排除AD,第一个空上的词要做主语，第二个空上的词做for的宾语，代替the old scientist。【标签】复合句

谢谢了