We don't know for sure how much mass our Sun's lost over the last four billion years.
我们不知道我们的太阳在过去的40亿年里损失了多少质量。
Scientists are continually learning more about sleep, but one thing they know for sure is this—for humans, it is as important as food and water.
科学家正在不断加深对睡眠的研究，他们对其中的一件事实确信无疑：对于人类来说，睡眠与食物和水一样重要。
We'd probably know for sure whether someone was shooting at the president from that famous grassy knoll.
我们可能确定是否有人正在从那个著名的草地山丘草地上向总统射击。
Do you remember all years when scientists argued that smoking would kill us but the doubters insisted that we didn't know for sure?
还记得那些年吗？当初，科学家提出吸烟会导致死亡，而怀疑者们却坚持认为我们还不能确认这一点。
Just as on smoking, voices now come from many quarters insisting that the science about global warming is incomplete, that it's OK to keep pouring fumes into the air until we know for sure.
就像吸烟一样，现在来自许多方面的声音坚持认为，有关全球变暖的科学是不完整的，在我们确定之前，继续向空气中排放烟雾是可以的。
Here's what we know for sure, based on comments from Microsoft execs.
下面是我们根据微软execs的回复所得到的信息。
Or it's a case of "won't dignify with a response" – we can't know for sure.
或者，这只是一种“不高贵的回应”情况，我们也无法确定事情的真假。
Sal: Hard to know for sure, but we believe in aloha 'aina: love of the land.
赛儿：确实很难讲，但是我们相信阿啰哈爱纳：对土地的热爱。
I don't know for sure whether the bank will grant him the loan he has applied for.
我并不确切地知道他申请的贷款(loan)银行是否会给。
We all desperately want to get it right and never know for sure whether we are.
我们都拼命的想做对的事却永远不确定我们做的到底对不对。
Do you know for sure that there aren't any memory leaks in your running services?
你能肯定的知道正在运行的服务里面没有内存泄露吗？
Indeed, that we can't always know for sure who did what or why becomes a powerful theme.
的确，我们不可能总是确定的说谁做了什么为什么这么做，这使得此书深入人心。
Don't buy your textbooks until you know for sure the teacher is actually going to use them.
不要买教科书，除非你确信你的导师会用到它们。
At that moment I realized that I needed to know for sure whether my dog was retarded or not.
那刻我受不了了，我一定要搞清楚，我的狗狗到底是不是真的智商有问题！
Maybe it'll never be right for your company, but you won't know for sure without giving it a try.
也许它永远都不会适合于您的公司，但是，如果不尝试一下，您就不会确切地知道这一点。
I'll never know for sure, because both stress and certain antidepressants can cause hair loss.
我无法知道确切的原因。因为压力和某些抗抑郁药物均可能引起脱发。
But the study results were not conclusive, and more research is needed before we know for sure.
但是研究结果并非盖棺定论，在我们确切明白之前还需要做更多的研究。
Alex rooms with Henry Thorpe, and since Henry is one of the senior prefects, he would know for sure.
阿列克斯和亨利·骚伯同屋，而亨利是四年级级长之一，他准知道。
Let me emphasize: This is the only time you will ever know for sure that disaster is about to strike!
我要强调一下：灾难的发生是不可预测的，但是灾难恢复测试时间是确定的。
Also, you can't know for sure what the other players are holding and what the next CARDS are going to be.
而且，你也不可能知道对手手里的牌是什么，下一张牌又是什么。
But because the parents do not know for sure how hungry their child is, they are liable to manipulation.
但是父母并不能确知孩子到底有多饿，所以还是容易上当。
If you fail this test then you know for sure that you are not gradient field so you might as well do that.
如果通不过检验，那么可以肯定，它不是梯度场，你可能也会那样做。
One thing I know for sure, to be good in my business I could simply meet the expectations of my passengers.
有一件事我深信不疑，想在这个行当中做得好，只要满足乘客的期望就行了。
One thing we know for sure is that the British economy will suffer its first recession for 18 years in 2009.
头一件我们可以肯定的事就是英国的经济将在2009年经受18年来的第一次衰退。
The business wants to reduce the cost of the process, but does not know for sure how much it costs per order.
企业希望降低流程的成本，但是无法确定每个订单的具体成本。
Though it is hard to know for sure when these photos were taken, they were all released in the last seven days.
虽然当这组照片被公布时人们很难去判断它的真实性，但是在过去的七天里他们还是全都公之于众中。
One thing I know for sure, to be good in my business I could simply just meet the expectations of my passengers.
我很清楚要干好这一行，需要做的仅仅就是满足乘客的期望。
We can't know for sure how many Kindles Amazon (AMZN) is selling, because the company refuses to release figures.
亚马逊到底卖出了多少台Kindle，我们不得而知，因为公司拒绝公布具体数据。
That's as much as we know for sure, but what is not clear is exactly how this SSO option will be presented to the user.
这些都是我们能确定的，而我们不能确定的是这个单一登录入口如何呈献给用户。
That's as much as we know for sure, but what is not clear is exactly how this SSO option will be presented to the user.
这些都是我们能确定的，而我们不能确定的是这个单一登录入口如何呈献给用户。
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