假定英语课上老师要求同桌之间交换修改作文，请你修改你同桌写得以下作文。文中共有10处语言错误，每句中最多有两处。错误涉及一个单词的增加，删除或修改。
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：把多余的词用斜线（\）划掉。
修改： 在错的词下划一横线，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处起）不记分。
Yesterday my friends or I visited a model high school. We start our visit from the main
building. First we went to the lab building in that some students were doing experiments. Then we entered in the lecture hall behind the lab building and saw many students listen to a lecture given a professor. Next to the lecture hall was the art center. There they watched groups of students playing musical instrument. On the playground some boys were playing the football. It was so exciting that we couldn’t help cheer for them. It was really an impressive visit.