Pinocchio was so near the fire that his wooden feet burned away. He did not feel anything. He slept and slept, ______ somebody knocked at the door.

【正确答案】 B

【答案解析】 suddenly(突然)，perhaps(或许)，yet(然而，已经，还)，instead(代替)都是副词。根据句意可知B项正确。