His father got him a job in a bank but soon it became clear he was not fit for that kind of work．
A. why
B. what
C. whether
D. that
网友回答
A. why
B. what
C. whether
(答案→)D. that
解析：that在此处引导一个宾语从句，that he was not fit for that kind of work 也可以理解成是宾语补足语，补充说明clear的内容，此处的that是不可省略的。