Neil：Hello and welcome to Authentic Real English, I'm Neil and joining me is Feifei…
Neil：I've got a medical experiment to perform on you in this programme, Feifei.
Neil：Come on – it's for our listeners. We've got an expression which means to react to something without thinking about it carefully first. So, cross one leg over the other, like that.
Neil：Keep calm – it's OK, I'm not going to hurt you. And I'll just tap your knee… And… it worked!
Feifei：Yes Neil, well done. You've just tested my reflexes. 你刚才检查的是我的膝跳反映，也可以被叫做膝跳反射。 When you hit my knee with the hammer, my leg kicked automatically. I didn't even think about it.
Neil：It was a knee-jerk reaction. And in English we can say that someone has a knee-jerk reaction when they act after an event without thinking carefully.
Feifei：Let's hear some examples of 'knee-jerk reaction'.
He left his wife after he saw her having a drink with another man but it was a knee-jerk reaction. He'll be back.
Putting up interest rates because of inflation is a knee-jerk reaction. They haven't thought of the other consequences.
Feifei：A knee-jerk reaction 本能反映。Acting automatically, without thinking about the consequences.
Neil：Let's try that again with the other knee. Here we go… Argh – you kicked me in the face!
Feifei：Sorry Neil – it was just a knee-jerk reaction.