题目内容：

假定英语课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。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：在错的词下画一横线，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。

For ages, sailors have said that it is a good luck to see dolphins swum alongside boats. Their presence meant that land is near, which will be vital informations if a boat and her crew are in danger. Some dolphins have even protected sailors which suffer shipwreck from sharks. There is no wonder that these unique and fascinating creatures have long know as our friends.

Dolphins are thought to be intelligent animals because of its quick ability to learn. They seem to communicate with each other through a combination of whistles and clicks. While scientists don’t know exact what they are talking about, it is thought dolphins are telling each other that food is nearby, or warming each other of approaching dangerous.