帮助一名学生提高英语写作能力。提供一篇短文，要求学生修改其中的语法、标点符号和用词，使其更具流畅性和可读性。给出修改后的短文。
原始短文：“I has been study english for three years. I thinks it is a very interesting language, but it is also very hard. My friend, who speak english fluently, say that practice is the key to improve. However, I find it difficult to practice with native speakers because I am afraid of making grammar mistakes.”
修改后短文：

I have been studying English for three years. I think it is a very interesting language, but it is also very challenging. My friend, who speaks English fluently, says that practice is the key to improving. However, I find it difficult to practice with native speakers because I am afraid of making grammar mistakes.