"Boy, why have you got cotton-wool in your ear? Is it infected?"

"No, sir, but you said yesterday that everything you told me 

went in one ear and out the other, so I am trying to stop it."

“孩子，你为什么用棉花塞住耳朵？它感染了吗？”

“没有，老师。可是你昨天说你告诉我的知识都是一个耳朵里进，一个耳朵里出，所以我要把它堵在里面。
 
【注释】

cotton-wool：棉花

infect：使受影响，感染