假如英语课上老师要求同桌之间交换修改作文，请你修改你同桌的以下作文。文中共有10处错误，每句中最多有两处。错误涉及单词的增加、删除或修改。
增加：在缺词处加一个漏词符号∧，并在此符号下面写出该加的词。
删除：把多余的词用斜线\划掉。
修改: 在错词下面划一横线，并在该词下面写出修改后的词。
注意：1. 每处错误及其修改均仅限一词；
2. 只允许修改10处，多者从第11处不计分。
Among the lesson I had in my schooldays, the one given by an American is the most unforgettably. One morning, our teacher told us he had been invited an American to give us a lesson. Then a man came in. He introduced himself with English and began his class. It was different from those classes they had before. He told many funny jokes, teaching us English songs and helped us act out dialogues. He neither taught us English grammar or asked us to do written exercises. He was not serious and was always smiling us. Time went quickly and after we knew it, the class was over. I will never forget his smile and everything he does in class.