I will never forget the teacher who taught us chemistry in the middle school.He was an ordinary-looking man and always wore a pair of thick glasses,but he had a strange way of making his classes lively and interesting.
One afternoon,the teacher took us to the Chemistry lab.There he taught us the first lesson【纵览全球英语资讯、洞察全球英文信息，尽在英语翻译学习网（enfanyi.com）你的全球英语指南】 in chemistry.
The teacher told us to watch carefully everything he did and then asked us to do the same.He poured some vinegar,kerosene and castor oil into a cup.After that,he mixed the three thoroughly.He dipped a finger in it.Then he sucked a finger and gave a smile.At last he handed the cup around the class.Each of us dipped a finger into the mixture,sucked it and made a face.The mixture tasted horrible.
At last we gave the cup back to the teacher.Now he shook his head sadly,"I'm sorry to tell you,"he said,"that you didn't watch carefully enough what I did.The finger I put into my mouth was not the one I had dipped into the cup."
