LOOK CAREFULY AND LEARNMy friend Pail will never forget his first chemistry teacher .He was a little man with thick glasses lively and interesting.And his lessons were not easily forggeten. Paul remember one of his first lessons from this teacher.After the students in the chemistry lab, the teacher brought out three bottles.One was filled with petrol,one with castor and oue with vinegar."Now wathch carefully," said the teacher .He then filled a cup with some of the petrol,some of the vinegar.As the students watched him quietly,he mixed the three together.After that,he held up one of his fingers and showed it to the class.He then dipped it into the cup .After a few seconds he took his finger out ."Now watch,"he said."remember ,you must do everythjing as i do ."He put a finger in his mouth,tasted it and smiled,looking rather pleased.Then he handed the cup around the class of studentds .Each student dipped a finger into the mixture and sucked it .Instead of smiling ,each of them made a face .The mixture tasted terrible.When the cup was at last returned to the teacher ,he said sadly,"I'm sorry,none of you watched carefully enough .Yes,I sucked a finger ,but the finger I put into my mouth was not the one I had dipped into the cup .It was Paul's first important lesson as a student of chemistry and he never forgot it ." 参考资料：课文
鹤顶红IF
