guarantee
单词辨析：
指以口头或书面形式作保证、担保、承诺，含若违背则予以补偿之意。
I can guarantee that he will pay off the debt.
我可以保证他会还清债务的。
I can't guarantee I will finish the work before dark.
我不能保证天黑前完成那项工作。
The law guarantees equal rights for men and women.
法律保证男女平等。
指用言语承诺某事一定会发生或一定是真实的，以消除他人的疑虑或担心。
I can assure you that your daughter will be happy here.
我可以向你保证，你女儿在这里会很快乐的。
We assured the tourists of an enjoyable holiday.
我们使游客确信准能过一个愉快的假期。
较正式用词，指向他人保证某人或某事物可靠、没有问题等。
certify sb's honesty and reliability
担保某人诚实可靠
I certify on my honour that she is innocent.
我用名誉担保她是清白无辜的。
指保证一定会做某事或提供某物，或某事一定会发生，侧重于自己的主观意向，用言语使人感到放心。
He promised to return the money to me.
他保证把钱还给我。
He promised her that he would marry her.
他保证要娶她。
指以发誓的形式作出保证，或强调自己所说的是真话。
He swore that he would get his revenge.
他发誓要报仇。
I never touched his wallet, I swear!
我绝没有碰过他的钱包，我发誓！
He swore never to gamble again.
他发誓再也不赌博了。
尤指公开或正式作出的保证。
The local government made a pledge to not compromise with terrorists.
当地政府保证决不向恐怖分子妥协。
Has he fulfilled his election pledge?
他履行竞选时的承诺了吗？
指强调某事一定会发生或肯定某事真实性的保证，尤为减轻他人的忧虑。
After my repeated assurances, she looked less worried.
经过我再三保证，她看起来不那么紧张了。
The tailor gave an assurance that her dress would be ready by Friday.
裁缝保证周五之前把她的裙子做好。
一般指对一定会做某事或某事肯定会发生的正式承诺。
The manager has given a guarantee that there will be no redundancies.
经理已经保证不会裁员。
Actually, there's no guarantee of success even if you can get the money.
实际上，即使你能得到那笔资金，也不一定会成功。
相关例句：
We guarantee to fulfil [ complete] our mission.
我们保证完成任务。
NATO says it will keep a reduced number of modern nuclear weapons to guarantee peace.
北约宣称将削减现代核武器的数量并将其维持在这一水平，以保障和平。
It was still under guarantee.
它还在保修期内。
He will sign a personal guarantee to additionally secure the loan.
他将签订一个个人担保，以此为贷款多加一层保障。
We cannot guarantee the accuracy of these figures.
我们不能保证这些数据的准确性。
All Dreamland's electric blankets are guaranteed for three years.
所有的梦乡牌电热毯质保3年。