英语情景对话：
A: Where are you going?
你去哪？
B: I’m going to the hospital.
我到医院去。
A: What’s the matter?
怎么啦？
B: Professor Wang was hurt in a traffic accident.
王教授遇到车祸。
A: That’s too bad. How are things going now?
真糟糕，现在请将如何？
B: His life is hanging by a thread, and he is under an emergency treatment.
他生命垂危，在抢救之中。
习语：
hang by a thread
解词释义：
hand是动词，意思是“悬挂，掉”，thread是名词，意思是“线”，hang by a thread意思就是“用一根线悬挂着”，相当于中文中的“千钧一发”，同样也可以理解为“危在旦夕”。
拓展讲解：
hang by a hair与上述习语同意。短语中的by a hair是一个短语，它的意思是“一点点，一点儿”。
支持范例：
（1）hang by a thread
Eg. The fire was approaching people's houses. people's lives and properties hang by a thread.
大火向民房逼近，人民的生命财产危在旦夕。
Eg. For some time after he dangerous operation, Keren's life hang by a thread.
在她作了有危险的手术后的一段时间时凯伦的生命处于垂危之中。
（2） hang by a hair
Eg. As his health deteriorates, he seems to hang by a hair of regaining his strength .
因为他的健康每况愈下，他似乎很难恢复精力。
Eg. As Jack's car ran into a truck his life hung by a hair.
杰克的车撞上卡车时,他的生命危在旦夕。
（3）by a hair
Eg. He escaped death by a hair's breadth. If the other car had been going any faster, he would certainly have been killed.
他简直是死里逃生. 要是那辆车开得再快一点, 他肯定被撞死了。
Eg. The bullet missed me by a hair's s breadth.
那颗子弹差一点就打中了我。
Eg. She won by a hair, while I lost the game by a hair.
她以微弱的优势获胜，可是我以微末的差距输了。
英语学习笔记：
1. in a traffic accident：在车祸中
Eg. When she heard that her husband had been killed in a traffic accident she went haywire with grief.
当她听说她丈夫在交通事故中身亡的消息时，她悲痛得精神失常。
Eg. Remember that you or I could drop dead from a heart attack or be killed in a traffic accident tomorrow.
要知道，你我都有可能明天因心脏病发作而暴卒，或者因交通事故而丧生。
2. under an emergency treatment：在急救中
Eg. Early in the morning he felt an acute pain in the belly and his parents had to send him to hospital and now he is under an emergency treatment.
大清早他感到腹部一阵剧痛，父母不得不送他去医院，现在在急救之中。
3. under treatment：在治疗中
Eg. The woman injured in the car crash is still under treatment in hospital.
在撞车事故中受伤的女士们妇女现在还在医院里接受治疗。
Eg. She is under good treatment in the hospital.
她在医院里正在接受很好的治疗。
