A. The teacher must learn everything by heart. B. He knows how to control his voice better than an actor. C. He has to deal with unexpected situations. D. He has to use more facial expressions. 参考答案:C 答案解析:[解析] 事实细节题。见第二自然段第二、三句。教师与学生之间是互动的,需要回答学生们的问题。