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。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()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。

    One Monday afternoon, we were playing the basketball on the playground while I suddenly slipped and fell over. On seeing that, all my classmates rushed to me. Under the help of several other students, Li Xiang, one of my best friend put me on his back and head for the clinic immediately. It turned out that my right ankle got injured but I had to be sent to hospital. He did not leave until an ambulance was arrived. The following day, he came to see me. To my greatly relief, he brought textbooks to them and helped me with my lessons. It was a great pleasure have such a devoting friend.

人类双眼皮为显性，单眼皮为隐性．某年轻夫妇均为单眼皮，生了一个单眼皮的女孩．后来母亲去美容院通过外科手术变成双眼皮，该夫妇如果再生一个孩子是双眼皮的机率为（  ）

There are ________ on the farm.