_______ in the storybook that he had bought not long before, the boy didn’t notice his mother go into his room.

_______ in the storybook that he had bought not long before, the boy didn’t notice his mother go into his room

1. A.
   Losing
2. B.
   Lost
3. C.
   Having lost
4. D.
   To be lost

_______ in the storybook that he had bought not long before, the boy didn’t notice his mother go into his room.