求新概念英语第2册第48课的背景

求新概念英语第2册第48课的背景
附原文：
Lesson 48
Did you want to tell me something?
你想对我说什么吗?
First listen and then answer the question.
听录音,然后回答以下问题.
Why did the writer become very worried?
Dentists always ask questions when it is impossible for you to answer.My dentist had just pulled out one of my teeth and had told me to rest for a while.I tried to say something,but my mouth was full of cotton wool.He knew I collected match boxes and asked me whether my collection was growing.He then asked me how my brother was and whether I liked my new job in London.In answer to these questions I either nodded or made strange noises.Meanwhile,my tongue was busy searching out the hole where the tooth had been.I suddenly felt very worried,but could not say anything.When the dentist at last removed the cotton wool from my mouth,I was able to tell him that he had pulled out the wrong tooth.
New words and expressions 生词和短语
pull v.拔
cotton wool 药棉
collect v.搜集
collection n.收藏品,收集品
nod v.点头
meanwhile adv.同时
参考译文
牙科医生们总是在你无法作出回答的时候向你提出问题.我的牙科医生刚刚给我拔掉了一颗牙,叫我休息一会儿.我想说点什么,但我嘴里塞满了药棉.他知道我收集火柴盒,于是问我收藏的米柴盒是否在增加.接着他又问我的兄弟近来如何,问我是否喜欢伦敦的新工作.作为对这些问题的回答,我不是点头,就是发出奇怪的声音.与此同时,我的舌头正在忙着寻找刚拔掉的那颗牙的伤口.我突然非常着急起来,但却什么也说不出来.当那位牙医最后将药棉从我嘴中取出时,我总算有可能告诉他,他拔错了牙.