that he made an obvious mistake, Jeff went on with his speech.
A. Not realized
B. Not to realize
C. Not to have realized
D. Not realizing
网友回答
A. Not realized
B. Not to realize
C. Not to have realized
(答案→)D. Not realizing
解析：考查非谓语动词。主语Jeff与realize之间够成逻辑上的主动关系，所以用现在分词。根据句意应为否定形式所以要在分词前加not.句意： Jeff 没有意识到自己犯了一个明显的错误，所以继续他的演讲。