Dear John，

　　Thank you very much for your invitations to dinner in your home tomorrow evening．It's been a long time since that we last met．Unfortunate，it is much to my regret that I cannot join you．I will be fully occupying in preparing for an importance lecture coming the day after tomorrow．I feel terribly sorry for missing∧chance for a get-together，and I hope that you'll have a good time with me．Maybe you and me can meet sometime next weekend．If so，please calling me when you get this letter．I think it was great to have a long chat with you．

　　Sorry again．

　　详

　　1．invitatoions改为invitation考查名词．此处"邀请"只有一份，应用单数形式．

　　2．去掉that考查连词．在英语中，两个单句只要一个连词，已有连词since，that是多余的，要去掉．

　　3．Unfortunate改为Unfortunately考查副词．修饰句子要用副词．

　　4．occupying改为occupied考查固定搭配．beoccupiedin意为"使忙碌于，使从事于"，是固定搭配．

　　5．importance改为important考查形容词．lecture是名词，其前用形容词修饰作定语．

　　6．加the考查冠词．chance后有介词短语for a get-together作后置定语，加the表示特指．

　　7．with改为without考查介词．根据句意：我希望你没有我会玩得高兴．用介词without．

　　8．me改为I考查代词．and是并列连词，它前后连接两个相同的语法成分，you和I是并列主语，都用主格代词．

　　9．calling改为call考查句子结构．祈使句中要用动词原形．

　　10．was改为is考查动词时态．此处讲述的是一般事实，用一般现在时态．