题目内容：

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10处语言错误，每句最多有两处。每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。

With the development of modern technology, there are a plenty of ways for us to contact people. WeChat is probably our favorite, mainly because of its convenient. We can keep in contact with friends whenever it is and wherever we are as long as Wi-Fi is available. Another advantage is it is a relative cheap and quick way of communication. As messages get send and received instantly, the cost of making phone calls is cut down. Besides, music as well as pictures and videos are often downloaded through WeChat, but it is now a useful entertainment tool. However, problems exist at the meanwhile. For example, your identity can be easily revealed, so we should pay attention to protect our personal information.