Knowledgeable as he is, the expert was unwilling to offer advice to he thought was not qualified.
A. whoever
B. who
C. whom
D. which
网友回答
(答案→)A. whoever
B. who
C. whom
D. which
解析：通过分析句子结构，可知这个句子中包含一个宾语从句。这个宾语从句作介词的宾语，引导词在宾语从句中作宾语，且表示“任何人”的意思，故用whoever。