这个谜题的答案在于早期光合生命形式的新陈代谢活动，这种活动缓慢但一定改变了地球大气的化学成分。
The answer to this riddle lies in the metabolic activity of early photosynthetic life-forms that slowly but surely transformed the chemical composition of Earth's atmosphere.
日久不一定生情，但一定可以见人心。
我不清楚菜谱上有什么，但一定很精彩。
I don't know what's on the menu, but I'm sure it will be good.
但一定不要给它危险的东西。
可以失望，但一定不要绝望！
参加够在厨房里到处爬，但一定不得触摸到地板。
You play by climbing around the kitchen without ever touching the floor.
这是一个相对快而且轻松的过程，但一定需要能忍受针刺。
This is a relatively quick and relaxing procedure, but does require a needle stick.
空虚无聊的时候就读书，但一定得有自己的生活目标和计划。
Emptinesss when I was reading, but must have their own life goals and plans.
空虚无聊的时候就读书，但一定得有自己的生活目标和计划。
Emptiness when I was reading, but must have their own life goals and plans.
对于一个商务约会，提早五分钟到是很合适的，但一定不要迟到。
For a business appointment, it is considered proper to be five minutes early, but never late.
当你很累的时候，你可以对自己说，我很累，但一定不要说，我做不到。
When you're tired, you can say to myself, I am very tired, but must not say, I can't do.
在能量网的不同点，能量生命或休息或工作，彼此不同但一定程度上有相似之处。
At various points in the web, creatures of power rest or work, each different from the others, but all somehow the same.
避免强光—如果半夜醒来后30分钟内不能再次入睡的话，干脆起床，但一定尽量避免强光。
Avoid BRIGHT LIGHTS - if you wake up in the middle of the night and can't get back to sleep within 30 minutes, get up but avoid as much light as possible.
无论你在家把地板打扫得多一尘不染，但一定还是会有一些小颗粒会进到你电脑的齿轮中，让事情变得更糟。
No matter how spic and span you keep your floors at home, there are still bound to be tiny particles down there that can get into your laptop's gears and mess things up.
早起，因为有事要做，但一定还要给自己来点激励性奖赏，要么给自己留点时间欣赏电视节目，要么轻松地走一走。
Get up because you need to get stuff done, but make sure you also give yourself a little motivational rewards, whether it be allotted time for a TV show, or a nice brisk walk.
可以在 config-store/index.properties 中找到可用配置，但一定不要更改该文件，因为这样可能破坏您的安装。
You can find available configurations in config-store/index.properties, but be careful not to change this file, because that might corrupt your installation.
你会受到一定程度的批评，但这是你必须面对的。
You are going to have to take a certain amount of criticism, but you must cope with it.
你一定认为我很无礼；但这一切对我来说都很新鲜。
虽然这些化学物质的简单存在并不一定表明存在健康风险，但典型的美国人身上携带这些化学物质的事实让琼和他的同事感到震惊。
While the simple presence of these chemicals does not necessarily indicate a health risk, the fact that typical Americans carry these chemicals at all shocked June and his fellow participants.
虽然这些化学物质的简单存在并不一定表明存在健康风险，但典型的美国人身上携带这些化学物质的事实让琼和他的同事感到震惊。
And while the simple presence of these chemicals does not necessarily indicate a health risk, the fact that typical Americans carry these chemicals at all shocked June and his fellow participants.
一定程度的气候变暖是确定无疑的，但其程度将由冰的融化、海洋、水蒸气、云和植物的变化等循环过程所决定。
Some warming is certain, but the degree will be determined by cycles involving melting ice, the oceans, water vapour, clouds and changes to vegetation and plants.
所有这些解释都有一定道理，但还不够充分。
There's some truth to all these explanations, but they aren't quite sufficient.
随着年龄的增长，人类的大脑具有了一定的数量本能，但这种本能是非常有限的。
Human brains come equipped with certain quantitative instincts that are refined with age, but these instincts are very limited.
但这并不一定代表幸福婚姻的增加，这一趋势也不太可能持续。
But this won't necessarily represent an increase in happy marriages, nor is the trend likely to last.
例如，做过股票交易所价格实验的曼德尔布洛特指出，尽管结果是可变的，但实际上存在一定的一致性。
Mandelbrot, who did the experiment with stock exchanges prices, for example, noted that although the outcomes were variable, there were, in fact, certain constancy.
它尽管在陈述观点的方面表现出明显缺陷，但总体是可理解且连贯的，并且表达上具有一定的流畅性。
It is generally intelligible and coherent, with some fluidity of expression, though it exhibits some noticeable lapses in the expression of ideas.
现在，他一定明白了；但一点也不明白。
现在，他一定明白了；但一点也不明白。
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