He might get there in time, but I can't be sure.

他有可能准时到达，但我不敢肯定。

《牛津词典》

I'm sorry, but I can't be sure about that.

不能保证会是这么个结果…但我会尽力做。

youdao

He might get here in time, but I can't be sure.

他可能及时来到这里，不过我不能确定。

youdao

And he said, "Well, I believe there's a God, but honestly, I can't be sure there's a God.

之后他自答到,"我相信上帝,但说实话,我不能确定上帝的存在

耶鲁公开课 - 心理学导论课程节选

The talk is that most of these guarantees are for credit derivatives, or insurance against Greece not paying its debts - but I can't be sure that's so.

BBC: Eurozone woes are US woes

There MIGHT be someone more worthy of first place, but I sure can't think of one.

NPR: The Best Living Songwriters