简单句偏多了;文中词汇表达不够丰富,同时请仔细检查词汇的拼写;层次欠清晰,衔接成分很少。
Dear John: I'm writing to you to tell you that maybe I can't have diner with your family . I'm so sorry and I'm grateful to your invite . The reason is we will have an important test the other day .What a pitiy.I can't stay with you this evevning . I hope you will have a good time ,my friend .If I have spare time ,I would call you .I wish that .