It may be that some have them already, but we cannot be sure.
也许有些人已经拿到了，但我们不能确定。
至于那个，我也不能肯定。
不过，他们还不能确定。
我不能肯定。
We cannot be sure whether our dreams will come true.
我们不能确定我们的梦想是否将成真。
The workers believe it was bin Laden, but cannot be sure.
这些劳工认为那就是本·拉丹，但无法确定。
Unfortunately I favor melanin but cannot be sure from the photos.
然而，我不能从这些图片中确信是黑色素。
Granting that he did say so, we cannot be sure what he really meant.
假定他那样说了，那也不一定是他的本意。
The researchers point out that there are many things they cannot be sure about.
研究人员指出，有很多事情是他们无法确定的。
He cannot be 100% sure because the transfer needs more time to be sorted out.
之所以不说100%，是因为转会还需要时间。
In case you cannot finish the task in time, be sure to let me know.
假如你不能按时完成任务，请务必告诉我一声。
If a forest fire cannot be extinguished, devastation is sure to ensue.
如果森林火灾不能被扑灭，灾害一定会随之发生。
This number cannot be changed so be sure to enter it correctly.
这个数字不能改变，所以要确保输入正确。
If you cannot go in person to New York, be sure to buy the catalogue.
如果你无法亲自去纽约观看这场展览，请务必去购买一本展会的介绍手册。
If you cannot return on schedule, be sure to inform the host family by phone.
若未能于预定时间返家时，须以电话向接待家庭报备。
Are you sure you want to delete this content index? This action cannot be undone.
是否确认删除该内容索引？该动作无法撤消。
Are you sure you want to delete this content index? This action cannot be undone.
是否确认删除该内容索引？该动作无法撤消。
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