老师说:“今天这堂课,我们一起来做两个关于耳朵的实验。”同学们听了,高兴极了。开始实验了。第一个实验是听电风扇的声音。老师把电扇调到第一档,电风扇的叶片开始慢慢转动起来,同学们屏息凝视,可是电风扇的声音太小了,同学们几乎都听不见;老师把电扇调到第二 The teacher said: “Today’s class, we work together to do two experiments on the ear.” "Students listened, very happy. Start experimenting. The first experiment was to listen to the fan’s voice. The teacher put the fan to the first gear, the fan blade began to slowly turn around, students stare breath, but the sound of the electric fan is too small, almost all the students can not hear; the teacher transferred the fan to the second