·PS结尾的问题
PS的结尾在我看来是从过去到将来的一个过渡和展望吧，简要介绍一下自己的近况，自己在学习工作基础之上对自己的未来有一个怎样的规划，自己申请去学校以后都研究些什么，自己在学有所成之后有怎样的职场打算等等，顺带可以吹吹所申请的学校，项目组以及自己的potential academic advisor等等，嘿嘿~~
·PS字数的问题
我觉得把PS写长还是相对来说比较容易的，按照我列出的雏形写上个三到五段，差不多也得有个1000字左右吧，嘿嘿!然而不同的学校会有不同的要求，这样实际上有形无形地就把字数给限制住了。
比如ASU的ECE系对PS就有如下要求：
Please write a one-page essay describing your academic and career goals. Address the following in your essay:
In which specific area do you wish to study?
Why should you be admitted to the program?
再比如Purdue的ECE系对PS也有要求：
A statement of purpose is required for all degree-seeking applicants. Please submit a statement of approximately 300-500 words concerning your purpose for undertaking or continuing graduate study, your reasons for wanting to study at Purdue, and your professional plans, career goals, and research interests. You also may explain any irregularities or special circumstances applicable to your background and elaborate on your special abilities, awards, achievements, scholarly publications, and/or professional history.
总而言之，PS要想写好是需要花费很大心思的，写了改，改了再改，自己改，别人改，一直到一个大家都认为没有修改的余地为止;另外，一定注意针对不同的学校撰写不同的PS。