De Broglie, 1924, in his PhD thesis says, if an electron has wave-like properties, this would be its wavelength.
1924年德布罗意在他的博士毕业论文中说道，如果一个电子具有类似波的性质，这就是它的波长。
If an impact is large enough, it can disturb the environment of the entire Earth and cause an ecological catastrophe.
如果（陨石撞击地球的）力度足够大，相撞会扰乱整个地球的环境，并引发一场生态灾难。
If an ant finds an outstanding hole—such as the inside of an acorn or a rock crevice—it recruits another scout to check it out.
如果一只蚂蚁找到了一个出色的洞穴——比如橡子或岩石裂缝的内部——它就会叫来另一只侦察蚁对洞穴进行检查。
If an eggbox doesn't specifically say "Barn", "Percher" or "Free Range", the eggs that it contains are almost certainly battery produced.
如果一个鸡蛋盒没有特别标明“谷仓”、“高处栖息”或“散养”，那么里面的鸡蛋几乎肯定是批量生产的。
If an interactive computer screen is to match a whiteboard in usefulness, it must be viewable from arm's length as well as from across a room.
如果一个交互式计算机屏幕要在实用性上与白板相匹配，它必须在手臂长度范围和横跨房间范围内是可视的。
If an ocean floor tectonic plate meets the edge of a continent and they push against each other, the heavier one sinks down and goes under the other one.
如果一个海底构造板块与大陆边缘接触并相互挤压，较重的板块下沉到另一个的下面。
If an individual is handicapped envionmentally, it is likely that his brain will fail to develop and he will never attain the level of intelligence of which he is capable.
如果一个人在环境方面有缺陷，他的大脑很可能无法发展，他将永远无法达到他所能达到的智力水平。
If an interview is too easy, it's a sure sign that you haven't got the job.
如果面试太简单，那必定表示你没得到那份工作。
If an injury is serious, they must call 120 for help.
如果伤势严重，他们必须拨打120求助。
If an open fire or cooking causes smoke in your home, find a way to fix it.
如果明火或烹饪导致室内产生烟雾，要想办法解决。
Recent research suggests that if an argument gets resolved, the emotional response tied to it is significantly reduced or almost completely erased.
最近的研究表明，如果争辩得到解决，与之相关的情绪反应会显著减少或几乎完全消失。
If an overweight person is having a large portion, I'll hold back a bit because I see the results of his eating habits.
如果一个过度肥胖的人吃了大份食物，我会克制一下，因为我看到了他的饮食习惯带来的后果。
If an adverse reaction to a drug is serious, consult your doctor for advice at once.
如果对药物的不良反应严重，就要立即咨询医生的意见。
If an infant does not cry out, it is unlikely to get the attention it needs to survive.
如果婴儿不哭闹，就不太可能得到维持生存所需的关注。
People sat impatient and frightened in the dark as if an unseen enemy had landed from Mars.
人们焦急不安、惊惶失措地坐在黑暗中，好像有一名来自火星的看不见的敌人已登上了地球。
He was as little disturbed or frightened as if an elderly cat and dog had walked into the room.
他既不感到不安或也不感到害怕，就像走进房间的是一只老猫和一条老狗。
Most meeting times can be changed, even if an exact time is given, Ghanaians are very relaxed and easygoing.
大多数会议的时间是可以更改的，即使给出了确切的时间，加纳人也非常放松和随和。
If an ancient animal had structures that looked like antlers, palaeontologists would argue that it probably used them as an elk or moose.
如果一种古代动物有看起来像鹿角的结构，古生物学家就会争论说它可能像麋鹿或驼鹿那样使用鹿角。
If an unknown person enters a home, the camera will send the owner a warning that will cause an alarm to sound on the owner's smartphone.
如果一个不知名的人进入家中，摄像头就会向主人发送警告，并在主人的智能手机上响起警报。
Mobile phone companies should consider whether a new charger is now needed with every handset if an old one after the unified standard can be recycled.
如果统一标准后的旧充电器能被循环利用的话，移动电话公司应该考虑是否还需要为每部手机都配一个新的充电器。
If an earthquake, hurricane or other disaster strikes your community, you might not have access to food, water, and electricity for days or even weeks.
如果地震、飓风或其他的灾害突袭你的家园，你可能会好几天甚至好几个星期都无法获得食物、水和电。
For example, it is commonly said that luck, good or bad, comes in threes; if an accident happens, two more of the same kind may be expected soon afterwards.
例如，人们常说，好运和坏运气都是三位一体的；如果发生一起事故，不久之后可能会发生两起同样的事故。
What happens if an implant ruptures?
如果假体破损了，会发生什么？
But what happens if an assertion fails?
但如果断言失败，会发生什么？
If an error occurs, the links will be red.
如果发生了错误，那么这些链接会变成红色。
If an attribute has no prefix, it has no namespace.
如果属性没有前缀，那么它就没有名称空间。
What happens if an error occurs when we run our client?
如果运行客户机时出现错误怎么办？
But what if an application doesn't fit within the framework?
但是如果应用程序与框架不相配该怎么办？
If an error occurs, an appropriate message will be displayed.
如果出现错误，那么将显示适当的消息。
If an entry exists, then delete the line containing the entry.
如果该条目存在，则删除包含的该条目的语句。
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