【正确答案】Dear Tom,
First of all, happy birthday to you! Thank you very much for inviting me to your birthday party. I really wish I could come, but I'm afraid to tell you that I can't make it because my parents will go to see me on that day. I will send you a cute toy I bought yesterday. Hope you would like it and have fun.

【答案解析】[解析] 1．电子邮件形式和句子长度不要太单调，有时短句和长句相夹显得灵活。 2．使用动词比系表结构更有力量，更加吸引人。 3．亲切、口语化的语言更加受欢迎。使用被动结构，会显得疏远冷漠。 4．电子邮件应写得简单明了，便于阅读，太长的内容可以用附件的方式发出。