I guarantee that he will appear in court.

我保证他会出庭。

《牛津词典》

"I can give my customers a promise: if you eat at Peony Restaurant, I guarantee that everything you get will be the safest and the best," Yang said.

杨说：“我可以向我的顾客承诺：如果你们在牡丹餐厅吃饭，我保证你们所吃到的一切都是最安全、最好的。”

youdao

I guarantee that if you take this medicine, you'll soon get well.

我管保你吃了这药就好。

《新英汉大辞典》

"We have a message for them." "They may not listen to us now, but I guarantee you they will listen to us in November when we vote the bums out!"

VOA: standard.2010.04.15

I guarantee, more than that In fact, the people who chose where we started off 33 chose in that range.

我保证,多很多的,实际上选33的人是在这个范围内选择的

耶鲁公开课 - 博弈论课程节选

It will help you to produce a lot of writing; I guarantee.

我保证这肯定能帮你们写出很多东西。

耶鲁公开课 - 1945年后的美国小说课程节选

If you offer unique content at a fair price, I guarantee people will pay for it.

FORBES: What 'Hung' And iTunes Teach About Nick Bilton's "Me Economy"

Give people a button that says "Home" and I guarantee they will push it.

WSJ: Why Driverless Cars Are Inevitable��and a Good Thing

"I guarantee this is one of the best places to do business in America, " he says.

FORBES: Biloxi Blues