I'm afraid he's more of a talker than a doer which is he never finishes anything.(·山

问题补充：

Im afraid hes more of a talker than a doer，which is he never finishes anything.(·山东)

A. that

B. when

C. where

D. why

答案：

A. that

B. when

C. where

(答案→)D. why

解析：很显然，前文所说的(他是一个空谈家而不是一个实干家)是下文(他一事无成)的原因，由此可知应该选why。