Are you absolutely certain about this?

你对这事绝对确信无疑吗？

《牛津词典》

They are less certain about the smallest planet.

他们对这颗最小的行星就不那么确定了。

youdao

Is the firm certain about what its customers value?

公司是否确定它的客户所珍视的东西？

youdao

The Georgian spokesman says he cannot be 100 percent certain about Russia's involvement,but notes that an investigation of specific involvement of Russian special services is underway.

VOA: standard.2009.05.05

We can't know anything certain about the eternal and the immortal world of Paradise Lost except through these faculties we have and those are uncertain, imperfect, fallen human capacities of reading.

我们无法了解任何确切的,有关中的永恒不灭的世界的认识,除非那些借助于已有的不确切不完美的阅读技巧。

耶鲁公开课 - 弥尔顿课程节选

If you want to find out about their background or about how they feel about a certain thing,

如果你想了解他们的背景，或者他们对做某一件事有什么样的态度，

What do you 课堂 - SpeakingMax英语口语达人

Only one thing is certain about owning multiple homes--your taxes will get more complicated.

FORBES: Homing In On Taxes

One expert is certain about something and another is certain about exactly the opposite.

FORBES: Move up http://i.forbesimg.com t Move down

The only thing certain about this complex procedure is that the result is wide open.

ECONOMIST: The Tory leadership