各种常见证明一般都有固定的开头，那就是this is to certify that...。
例1：学历证明（certification of educational background)
certificate
this is to certify that mr. jiagn tao, male, born in shexian county, anhui province, in 1963, was admitted into the department of computer science and engineering of nanjing university in september 1983, majoring in computer application. he graduated from the university in july 1987 with a degree of bachelor in computer engineering.
nanjing university
june25,1991
例2：健康证明
health certificate
this is to certify that mr. wang hongjiang, male, aged 62, professor of anhui education college, his health is excellent and capable of going to japan to attend the 9th mathematics and statistics conference.
zhang wang
physcian-in-chief
anhui provincial hospital