He was uncertain about his brother's intentions.

他对他兄弟的意图心中无数。

《柯林斯英汉双解大词典》

But many young researchers, especially those who have not been mentored in open science, are uncertain about whether to share or to stay private.

但许多年轻的研究人员，尤其是那些没有接受过开放科学指导的人，对于该分享还是保持隐私是不确定的。

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For example, a company may be able to estimate accurately the aggregate number of shoes it will sell, but it may be uncertain about which specific types of shoes will sell more than other types.

例如，一个公司也许能够准确地估计它将销售的鞋子总数，但它可能不确定哪一种特定类型的鞋子将比其他类型的鞋子卖得更多。

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says the whirlwind of activities leading up to the Oscars leaves him uncertain how he feels about his nomination as best actor.

VOA: standard.2010.02.18

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

And So, Descartes used the method of doubt to say there's something really different about having a body that's always uncertain, from having a mind.

因此,笛卡尔运用怀疑方法得出,与拥有不可确定的身体不同,拥有心理是肯定的

耶鲁公开课 - 心理学导论课程节选

This leaves us uncertain about the effects of any particular rise in atmospheric CO2.

FORBES: Global Warming Will Increase Tropical Forests

Traders are more uncertain about the EU situation spreading into a worldwide debt contagion.

FORBES: Comex Gold, Silver End Higher as Gold Sets Another New Record High

The debts are due, personal wealth has been demolished, and people are uncertain about the future.

NPR: Hunkering Down In Recession: A Return To Thrift?