Are you certain this is what you want to do?

你能肯定这是你想做的吗？

youdao

He then further asked him: 'Are you certain that you will live another seventy years?'

他接着问：“你肯定自己能再活70年吗？”

youdao

Country folk can tell you that there are certain places which animals avoid.

乡下人会告诉你有些地方动物是不去的。

《柯林斯英汉双解大词典》

It cannot be priced at a level where only certain people have access, because then you are cutting entire sections of our country out of involvement in the world,"

VOA: standard.2010.01.05

Any frequency can't have an energy, you have to -- you don't have a continuum of frequencies that are of a certain energy, it's actually punctuated into these packets that are called photons.

任何频率不能有个能量,你必须要-对某一个能量上,你不会有连续的频率,光子实际上分立的存在。

麻省理工公开课 - 化学原理课程节选

Either that you are certain of something, that you are not certain of something,

一种是表达你对某件事情很有把握或者并没有什么把握，

I'm sure 课堂 - SpeakingMax英语口语达人

Are you certain all corporate access is shut down once a consultant leaves your organization?

FORBES: The $100 Billion Problem No One Is Talking About

Are you certain it cannot be stolen by people who have access to it?

BBC: Lib Dems 'may ditch' Communications Data Bill

Are you certain your employees do not send intellectual property or private data over any Internet channel, including Gmail and Facebook?

FORBES: The $100 Billion Problem No One Is Talking About