题目

火的使用是人类利用自然力的一个重大进步。迄今为止的考古证明，我国最早使用天然火的原始人类是(   ) A.元谋人                B.北京人             C.河姆渡人              D.半坡人 答案：A －Why did you talk to the teacher after class? －I don't understand ________ during the lecture． [　　] A． the problem did she tell us B． how did she say C． that she was talking about D． what she was teaching