短文改错。
假定英语课上老师要求同桌之间交换修改作文，请你修改你同桌写的以下作文。
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）不计分。
I am a senior high school student. To my opinion, the classroom is a place for students to gain
knowledges. So quietness is badly need for us to learn in the classroom. But recently some students
has brought their mobile phones to the classroom and we often hear of the ring of mobile phones.
Some of them even wasted precious time in class type short messages on the mobile phones. To
keep the classroom quietly and make us focus more on our studies, I suggest that mobile phones
be used in the classroom. At least, they shouldn't be used where we are having a class.
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