增加：在缺词处加一个漏字符号(^)，并在其下面写出该加的词；
删除：把多余的词用(\)划掉；
修改：在错的词下画一横线，并在该词下面写出修改后的词。
Today we had the honor of inviting Professor Boucher, foreign teacher from Beijing University, to give us an English lesson. All of us were deep impressed by the unforgettable English lesson. Professor Boucher began the class about an amazing English story which attracts our attention at once. He spoke slowly and clearly so that we could followed him well. Greatly inspired, most of them took an active part in classroom activities. After class, many students interviewing spoke highly of him. They said that they had never been experienced such interesting a class. From his lesson, we came to the conclusion which it is not difficult to learn English well if we find a good way.
