PS是很正规文书，不要用些口语化词语（kinda， sort of， wanna， it＇s， can＇t， shouldn＇t），最好让英语好人帮你改改。作为一个留学生，能把PS写通顺流畅绝对是加分项。
Currently a student of chemistry at the Beijing Normal University， I am scheduled to graduate in June 1998 with a B. S. degree. The university has offered， on the basis of my outstanding academic record， to exempt me from the usually mandatory examinations for graduate studies， should I decide to join its M. S. program. After weighing all the pros and cons， I now prefer to pursue my graduate studies with your university， as I think it will put me on better footing for my career.
My interest in science in general and chemistry in particular was first fostered by my family， which has， for several generations， been made up of professionals. My grandfather graduated from the University of Minnesota with a Doctoral degree in engineering， a highly unusual accomplishment for a citizen of mainland China in those years. My father， a professor of mathematics， was my main source of inspiration during the three years when I studied with the Beijing Mathematics Olympic School. My mother， a senior engineer of chemical engineering， was the motivation behind me as I participated in a variety of scientific activities such as the Solar Energy Club. Such a family environment has bestowed on me a gift for natural science that I have never failed to take advantage of. It has been my dream to become an outstanding expert in the field of chemistry.
Since I entered into the university over three years ago， I have studied diligently and conscientiously. With that， I have acquired a solid background in chemistry， mathematics and physics. With an overall GPA of 92. 29/100， I have， for three years running， kept myself as the very top student among the 114 undergraduates of my grade. I have not confined myself to my coursework， however. I have frequented the library and probably read more chemistry literature than most of other students. By satisfying my thirst for more knowledge， I have kept myself abreast of the new developments in chemistry around the world. I have also excelled in mastering foreign languages. Although I have never majored in the study of any particular language， my English proficiency has been improved to a point where it is comparable to that of most English majors in Chinese universities， and for that， I have been exempted from having to take an English course in the upper years. In recognition of my consistent excellence， I have been awarded the First-Class Excellent Academic Scholarship for three year.
Education at the Beijing Normal University emphasizes the importance of hands-on experience. In the summer of 1995， I joined Professor Tian＇s team to work o the synthesis of inorganic materials. In 1996， professor Guo made me a member of his research team， which gave me good exposure to unsymmetrical synthesis. I am now carrying out （sophisticated） experiment under the direction of Dr. Wang. Through these arrangements， I have gained good experiences in laboratory research and greatly improved my skills for scientific experimentation. Starting from the beginning of next semester， I will be writing my graduation paper under the seasoned guidance of professor （zhong kexue）， a research fellow from the Chinese Academy of Sciences.
As the Beijing Normal University specializes in training teachers， I have also taken quite a number of general education courses， such as phycology， pedagogy and teaching methods. And earlier this year， I was awarded the Excellent Teaching Assistantship for my outstanding performance during the internship at a high school.
I did not allow my heavy load of study to deter me from taking part in extracurricular activities. As the chair of the charity survives committee on campus， I honed my organizing skills and augmented my work efficiency. Convinced that the meaning of life comes from helping others， I have always been most obliging whenever anyone comes to me for help， which has won me lots of friends. Such personality， combined with my intellectual vigor and determination， should stand me ready for any challenges.
I am applying for acceptance into your program because I know that your country has leading the way in the development of chemistry， and I would like to put myself on the cutting edge of the field. I believe that your graduate school can offer the kind of academic quality and environment that I need. I am particularly interested in analytical and physical chemistry， as I have been fascinate by both its theoretical foundations and its practical promise. I am also interested in polymer chemistry and environmental chemistry. The completion of graduate studies with your program will not only enable me to realize my most cherished childhood dream but also put me in a much better position to serve my country.
I would greatly appreciate it if you could give favorable consideration to my application for acceptance and financial aid.
(英文全称Test of English as a Foreign Language,简称TOEFL)由美国教育考试服务中心主办，专门用来测试非英语国家学生的英语水平和掌握英语的熟练程度一种考试。
(英文全称Scholastic Assessment Test,简称SAT)是由美国教育考试服务中心举办的学术水平测验考试。SAT是美国高等院校决定录取和评定奖学金发放的重要参考标准之一。SAT分为SATⅠ和SATⅡ两部分，其中SATⅠ为推理测验，SATⅡ为专项测验。
SAT全称是Scholastic Aptitude Test;由美国的大学理事会(College Board)举办。SAT成绩是世界各国高中生申请美国名校学习及奖学金的重要参考。
(英文全称American College Test,简称ACT)与SAT一样，也是美国高等院校决定录取和评定奖学金发放的参考标准之一。ACT同样被很多美国大学承认，以美国中部和西部的院校居多。
(英文全称Graduate Record Examination,简称GRE)是美国留学申请研究生的入学考试，适用于除了法律(需LSAT成绩)与商业(需GMAT成绩)以外的其他各种学科与专业的研究生考试。它是美国研究生院选拔培养高级研究人才的重要依据，也是各大学研究生院决定是否向申请人提供奖学金资助的重要参考条件之一。
(英文全称Law School Admission Test,简称LSAT)，是美国法学院入学委员会法学院设置的入学资格考试，这些法学院多数分布在美国，少量在加拿大。几乎所有的法学院都要求申请人提交LSAT成绩，其成绩作为法学院评估申请者的主要条件之一，是一项非常重要的衡量标准。