证明书种类很多，有工作经历证明、工作经验证明、病情证明、留学生经济担保书、学业成绩证明书等等，是用来证明一个人的身份、学历、婚姻状况、身体情况等或某一件事情的真实情况。证明书的写法通常也采用一般信件格式，但多省掉收信人的姓名、地址和结束用语。称呼多用“To Whom It May Concern”意即“有关负责人”，但此项也可省略。写证明书要求言简意赅。

例一：医院证明

Doctor's Certificate

June 18, 2000

This is to certify¹ that the patient, Mr. Tomas, male, aged² 41, was admitted into our hospital on June 9, 2000, suffering from acute appendicitis³. After an immediate⁴ operation and ten days of treatment, he has completely recovered and will be discharged on June 19, 2000. It is suggested that he rest for one week at home before resuming his work.

Jack⁵ Hopkins

Surgeon-in-charge

医生证明书

兹证明病人托马斯先生，男，41岁，因患急性阑尾炎，于2000年6月9日住院。经手术和十天治疗后，现已痊愈，将于2000年6月19日出院。建议在家休息一个星期后再上班工作。

主治医生：杰克。霍普金斯

2000年6月18日

例二：公证书

Certificate

（90）Lu Zi, No. 1130

This is to certify that Mr. Zhao Qiangwen holds a diploma issued to him in July, 1980 by Shandong University（Diploma No. 064）and that we have carefully checked the seal of the University and the signature of President Zhou Yongsen.

JinanNotary Public Office

ShangdongProvince

People's Republic ofChina

Notary：Wang Fang⁶

May 2, 2000

公证书（90鲁公证字第1130号）

兹证明赵强文先生持有的山东大学于1980年发给他的064号毕业文凭上的学校印签和校长周永森签字属实。

                                                                                                                                                                                中华人民共和国

                                                                                                                                                                           山东省济南市公证处

                                                                                                                                                                            公证员：王芳

                                                                                                                                                                         2000年5月2日