假定英语课上老师要求同桌之间交换修改作文，请你修改同桌写的以下作文。文中共有10处语言错误，每句中最多有两处。每处错误仅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。
Boys and girls,
To make better use of the books we have used but no longer need them, we've planned to set up the book bank. We can recycle books and magazines that is in good condition in an effective way, thus avoided unnecessary waste. Meanwhile, the notes in our books can help another students learn their lessons efficiently than before. What's equal important is that, by using the recycling books, a lot of money can be saved.
Therefore, it's necessary that the Senior 3 students generously donate the used books and other learning materials, that will definitely serve as excellent examples for the students in those lower grade.
Thank you!
Student Union
，阿伏加德罗常数为NA．下列判断错误的是 （ ）