in the storybook that he had bought not long before, the boy didn’t notice his mother go into his room.
A Losing
B. Lost
C. Having lost
D. To be lost
网友回答
解析： 考查非谓语动词做状语.现在分词表示正在进行的动作,故去分词表示发生过的,被动的动作,不定式表示将要发生的动作.完成时表示已完成的动作.根据题意,可知这个男孩是lost的对象,迷失的,故选B,沉迷在故事书中.