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。

    It is fine day today and I will never forget this special day. I was chosen to be a member of the football team and send to take part in the school football match. I was excited, but believed I would score most. But in the first round I hurt my leg and couldn't but to give up. I felt very sad. My best friend Tom comes up to me and said, “You are great! You still played for a few minute even after your leg hurt. You are a true winner.” I couldn't believe my ears. For me the one scoring the most is the winner. But Tom said, “The one which tries his best is the really winner.” Deeply impressing by his words, I want to say “thank you” to him.

若不等式x²+ax+1≥0对于一切x∈（0，$\frac{1}{2}$）成立，则a的取值范围是（　　）