Language points

（Attention： The following points are not covered by the video. It is better for you to watch the video or listen to the MP3 first and try to take notes on your own. Then you may check here to get more details. ）新概念英语

1, On the other hand, your stomach would turn at the idea of frying potatoes in animal fat
 on the other hand 转折连接词，表示而另一方面
      at the idea of: at 介词搭配作状语，表示当......就......；一......就......
      at the idea of 一想到
      at the sight of 一看到
      at the mention of 一提到
      at the news of 一听到......消息
      at the touth of 一触摸到......东西
      at the sound of 一听到......声音
     at the thought of 一想到
Eg.: I was glad at the thought of getting something te eat.
        I always love at the mention of ghost story.
 
2, the normally accepted practice in many northern countries
 practice 表示习俗，做法
      habit表示个人习惯
      custom社会的风俗或习俗
Eg.: Early to bed and early to rise is good habit.
It is now quite common practice for married women not to take their husband’s second name.
the custum of giving present at Christmas