Eye of newt goes into the little black bag, if and only if there is reproducible scientific evidence that it works.
当且仅当有可重复的科学证据证明蝾螈之眼有效时，蝾螈之眼才会进入小黑袋中。
If they need to use others' words, they need to quote them and give the page number, even if it is only one word.
如果他们需要用到别人的话语，那么他们就需要引用并给出页码，即使所引用的只是一个单词。
Certain plant species won't flower if they sense too much light and some plants will only flower if they sense a specific amount of light.
某些植物种类如果感觉到了太多光就不开花，而有些只有感觉到了一定程度的光才会开花。
If you're standing nearby, the birdhouse will also give you a free Wi-Fi connection—but only if pollution level is low enough.
如果你站在附近，鸟舍也会给你免费 Wi-Fi 连接，但前提是污染水平得足够低。
Even if they don't, at least they will always know that they can live without computers, electricity, and smartphones—even if it is only for a few days!
即使他们不这样做，至少他们将永远知道，他们可以在没有电脑、电力和智能手机的情况下生活——即使只有几天！
This is true as the above derivation for a and b of opposite parity is an if and only if statement.
这是正确的，因为上面对a和b 的奇偶性的推导是一个当且仅当命题。
You are allowed to specify the value of the type parameter if you like, but only if you can name the type - and the capture types are not denotable.
如果愿意，您可以指定类型参数的值，但只有当您能够命名该类型时才可以这样做—并且不能够表示捕获类型。
If there is no friction, if there are no other forces, only gravity.
如果没有摩擦力，如果没有其他力，只有重力。
Eye of newt goes into the little black bag, if and only if there isreproducible scientific evidence that it works.
把蝾螈眼放入黑色的小袋子，当且仅当有重复性的科学证据表明它的实用性）。
A good deductive argument is sound if and only if it's both valid and has true premises.
一个好的演绎论点是完好的，如果且仅如果这些都有效，并且前提为真。
To see this yourself, design a small test program that will compile if and only if the desired condition is true.
为了能切身体会，您可以设计一个小测试程序，这个程序当且仅当期望的条件得到满足时才可以编译。
“All this will work if, and only if, the different countries are likely to do what they have to do in terms of restructuring the banking sector, ” he said.
“所有这些当且仅当不同的国家愿意做他们必须做的——重组银行业——才会起作用，”他说。
Make sure an HTTP 200 response is sent back if and only if the response was successful and the returned data is the expected one.
只有在请求确实成功了而且返回的数据就是期望的数据的情况下，才应该发送回http响应码200，必须确保这一点。
And with the first down beat, the drums roaring at the rear of the stage, I knew I'd reached that childhood goal of being "the leader of the band," if only for a moment, if only for a single piece.
随着第一个敲击声的落下，随着鼓声在舞台后方鸣鸣作响，我知道，我达成了童年时想成为“乐队指挥”的目标，哪怕只是一小会，哪怕只是指挥一首小乐曲。
The previous exercise shows that individual residents gain from their marginal contribution if and only if the park is smaller than.
以上练习表明当且仅当公园面积时，居民捐款的边际收益是为正。
And the reason for that because an argument is valid if and only if there are no possible situation in which all its premises are true and its conclusion false.
原因是因为论点有效，如果且仅如果没有可能情况，所有的前提都为真结论为假。
Let me remind you again that an argument is valid if and only if the premises are true the conclusion must be true.
我再来提醒一下，论点有效，如果且仅如果前提为真，结论肯定为真。
Please note: This file is generated if and only if the project is built.
请注意：该文件当且仅当项目构建时生成。
If a project has a unique IRR, we can state that the project increases the value of the company if and only if the project's IRR exceeds the annual cost of capital.
如果一个项目有唯一的IRR我们指出项目增加公司价值当且仅当项目的IRR超过年资金成本。
That is, a channel guard is ready if and only if the process at the other end of the channel has output to it and this data has not yet been input by this process.
也就是说，只有在通道另一端的进程已经输出数据，而该数据还没有被进程输入的时候，警卫才就绪。
That is, society will reward you with a remarkable life if and only if you can offer in return a useful and rare service.
社会奖励你的非凡生活仅是作为对你向社会提供珍稀服务的回报。
If, and only if, you use a third-party anti-virus program that is also anti-malware (the best ones are), you can also disable the Windows Defender service.
如果，仅仅如果你使用第三方反病毒程序同时也是反恶意软件程序(最好是这样)，你也可以禁用Windows保护服务。
For instance, a good test assertion is a JUnit test that returns true if and only if the SOAP envelope returned by a Web service is identical to a pre-defined XML document.
例如，一个较好的测试断言为JUnit测试，即当且仅当Web服务返回的SOAP信封与预定义的XML文档完全相同时，返回true。
If, and only if, the site reaches their goal of 1 million visitors will that "lucky blogger" receive any money.
只有网站访客数量达到一百万之后，“幸运的博客作者”才能拿到奖金。
The filter evaluates to true if and only if number of total occurrences (including the current one) is a multiple of 3. Figure 21 shows what the completed filter will look like.
当且仅当事件的总发生次数(包括当前发生的事件)为3的倍数时，该筛选器才求值为True。
The Bondareva-Shapley theorem:The core of the game is non-empty if and only if the game is balanced (Bondareva 1963, Shapley 1967).
Bondareva-Shapley定理：只有而且仅有当博弈是平衡的时候，中心才非空。
Remember that you execute the body of an if statement only if the expression is True, which for this expression happens when the variable I is not evenly divisible by 25.
记住，您只在表达式为True时执行if语句体。该表达式在当变量i不能被25整除时计算为True。
Last but not least, the XSL: if instruction executes only if its test succeeds.
最后但并非最不重要的一条指令就是xsl：if，它只在其测试成功的情况下才会执行。
So I want to say to my supporters: When you hear people saying or think to yourself, "If only, or, "What if," I say, please, don't go there.
我要告诉我的支持者：如果你听到别人说，或者你自己曾经这样想，“如果某件事没有发生”，或者“要是出现了另一种情况”……那么我会说，请不要这样设想。
So I want to say to my supporters: When you hear people saying or think to yourself, "if only, or," What if, "I say, please, don't go there."
我要告诉我的支持者：如果你听到别人说，或者你自己曾经这样想，“如果某件事没有发生”，或者“要是出现了另一种情况”……那么我会说，请不要这样设想。
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