Although he talked half an hour, he couldn't give us a good of the reason why he did it.
A. idea
B. explanation
C. sense
D. understanding
网友回答
A. idea
(答案→)B. explanation
C. sense
D. understanding
解析：选择B。根据句意：他谈了半个小时，但就那件事，仍未能给出一个合理解释。
explain,名词为explanation.