Having said that, I did not know for a long time what I was looking for.

话虽如此，很长一段时间里，我都不知道自己追求的是什么。

youdao

But he added, he did not know for certain.

但是他补充说，他也不确定。

youdao

Mr Suttles said he "did not know for certain" why it had failed.

Suttles先生说他“并不十分确定”前种方案失败的原因。

youdao

Experts do not know for sure about his mother,Caterina.

VOA: special.2010.09.15

It is not about providing opportunities for people to get to know each other and to build friendships.

不是为人们提供机会,互相了解,建立友谊。

麻省理工公开课 - 媒体、教育、市场课程节选

I, I can't imagine not taking some kind of humanities class, just as a requirement, you know, for freshman.

对于新生，我实在无法想象不把人文科学当作必修课。

斯坦福的新生 - SpeakingMax英语口语达人

He added that the midwife concerned could not know for certain who she had visited without the diaries.

BBC: Poole hospital midwife patients' details lost in theft

We may not know for a long time what kind of impact these deployments are having on our children.

CNN: When a parent goes to war, military kids grow up fast

Yahoo said it did not know for sure that the file had been taken but told AFP it could not "deny the possibility".

BBC: Millions hit by Yahoo Japan hack attack