He was uncertain about his brother's intentions. [+ about]

他拿不準他哥哥的意圖是什麽。

They were uncertain of the total value of the transaction. [+ of]

他們還不確定這筆交易的總價值是多少。

He stopped, uncertain how to put the question tactfully.

他停頓下來，猶豫着該如何巧妙地提出那個問題。

With some hesitation and an uncertain smile, she held out her hand.

她猶豫了一下，帶着遲疑的微笑把手伸了出去。

How far the republics can give practical help, however, is uncertain.

然而，這些共和國究竟能夠提供多少切實可行的幫助還未可知。

It's uncertain whether they will accept the plan.

還不確定他們是否會接受這一方案。

Students all over the country are facing an uncertain future.

全國各地學生前途未蔔。

She told him in no uncertain terms to go away.

她明白無誤地叫他離她遠遠的。