I think she is either a Canadian or a German, but I am not sure.

我认为她要么是一个加拿大人，要么是一个德国人，但是我不确定。

youdao

I am not sure whether this was courage or pigheadedness.

我不确定这是勇气还是顽固。

《柯林斯英汉双解大词典》

I am not sure that this is sound democratic practice.

我不能肯定这就是正确的民主做法。

《柯林斯英汉双解大词典》

But now, I am not so sure that the wine is really Amontillado."

VOA: special.2009.02.07

I am not sure... Everyone was gushing about all the... I think it's modern arts.

我不是很确定……每个人都在滔滔不绝的讲……我认为是现代艺术吧。

喜欢毕加索吗？ - SpeakingMax英语口语达人

I don't know about that. I am not so sure." But then, we realized that like when we walk out that door, it's the whole world again. So you get sucked up by your group, by your sort of identity.

我不知道，不是很确定，然后呢，我们就意识到走出那个大门，又是一个完整的世界，所以你就会,被你的团体，你的身份所束缚。

普林斯顿公开课 - 人性课程节选

Whether the information I was given by the source is correct I am not sure.

FORBES: Chuck Hagel And The Lifecycle Of A Media Lie

Quite how anyone could suggest this with a straight face I am not sure.

FORBES: European Union Peace Prize: Nobel Committee Jumps The Shark

But with Mitsui or not, I am not sure.

FORBES: Magazine Article