certify

prove, certify, demonstrate, establish, testify

这些动词均含有“证明、证实”之意。
prove: 普通用词，指通过某种手段或方式提供证据以验证某事物真实与否，某结论正确与否等情况。
certify: 较正式用词，多指有签字盖章的、合符法律程序的书面证明。
demonstrate: 指通过推理、辩论、实验或以实例来确定事物的正确与否。常用于理论、学说、定律等的证明上。
establish: 指证实事实或理论的真实性与正确性，使其能长期存在或为人们所接受。
testify: 较正式用词，既指出庭作证，提供证据，又指为某人或某事的是否真实提供证据或证明。

动词 certify:

1. provide evidence for; stand as proof of; show by one's behavior, attitude, or external attributes
   同义词：attest, manifest, demonstrate, evidence
2. guarantee payment on; of checks
3. authorize officially
   同义词：license, licence
4. guarantee as meeting a certain standard
   同义词：endorse, indorse
5. declare legally insane

1. I certify that this is a true copy.
   我证明这是真副本。
2. I can certify to her honesty.
   我可以证明她是诚实的。
3. I certify that he has received your money.
   我证明他已经收到了你的钱。

cer.ti.fy

v.（动词）
cer.ti.fied,cer.ti.fy.ing,cer.ti.fies
v.tr.（及物动词）

To confirm formally as true, accurate, or genuine.
确认：正式确认为真实、准确或真正的
To guarantee as meeting a standard:
证明…合格：
例句：
butter that was certified Grade A.See Synonyms at approve
验证为A级的黄油参见 approve

To acknowledge in writing on the face of (a check) that the signature of the maker is genuine and that there are sufficient funds on deposit for its payment.
签名：银行在支票正面（签署）确认签名人笔迹为真实及有足够的供支付用的存款
To issue a license or certificate to.
颁发执照：给…颁发执照或证书
To declare legally insane.
法律上宣告为精神失常
Archaic To inform positively; assure.
【古语】 使确信：斩钉截铁地告知；使确信
v.intr.（不及物动词）
To testify:
证实：
例句：
certify to the facts.
用事实证明

来源：
Middle English certifien
中古英语 certifien
from Old French certifier
源自 古法语 certifier
from Late Latin certific3re
源自 后期拉丁语 certific3re
Latin certus [certain] * see certain
拉丁语 certus [肯定] *参见 certain
Latin -fic3re [-fy]
拉丁语 -fic3re [后缀，表.使…化.]

【引伸】
cer.tifi.er
n.（名词）