They say they are not sure whether the agreement will ever be fully implemented.

VOA: standard.2009.09.15

I might not be sure whether the opponent, whether my opponent, is choosing Left or Right.

我可能不太确定,我的对手会选择左还是右

耶鲁公开课 - 博弈论课程节选

I'm not sure whether this really should be called a coma.

我不确定这是否真的该被称作昏迷。

耶鲁公开课 - 死亡课程节选

"If you ask them whether they will receive a pension and what age, they say "I'm not sure whether I will be in the position of pensioners of today."

VOA: standard.2010.06.16