Leaving the most important tip for being a good guest is to know when to say goodbye.
作为一个好客人，给你最重要的提示是知道什么时候说再见。
The drone can know when to bring a cup of coffee by studying a person's personal information.
通过研究一个人的个人信息，无人机可以知道什么时候该带来一杯咖啡。
Anyone who has toiled through SAT will testify that test-taking skill also matters, whether it's knowing when to guess or what questions to skip.
任何一个曾经辛苦地经历过SAT考试的人都可以证实，应试技巧也很重要，即是否知道什么时候该猜测答案或者什么样的问题该跳过去。
When young people are critical of an over-tweeting president, they reveal a mental discipline in thinking skills—and in their choices on when to share on social media.
当年轻人批评一位过度发推特的总统时，他们在思维技能以及选择何时在社交媒体分享方面展现出一种精神自律。
So when young people are critical of an over-tweeting president, they reveal a mental discipline in thinking skills and in their choices on when to share on social media.
所以当年轻人指责总统过多使用 Twitter的时候，他们在思维方式上以及选择何时在社交媒体上分享的方面表现出了一种精神自律。
The problem lies in deciding when to intervene.
问题在于决定何时介入。
We discussed everything—when to go, what to see and so on.
我们什么都商量过了—什么时候走、看什么等等。
Let's discuss when to go to the Sea World.
让我们讨论一下什么时候去海洋世界。
The wind conditions decide when to fly or cancel.
风的状况决定了何时起飞或停止。
Did Alice tell you when to get to the station?
爱丽丝告诉你什么时候到车站了吗？
Mr. Zhang asked us when to go to dance classes．
张先生问我们什么时候去上舞蹈课。
Were you told when to arrive at the train station?
有人告诉你什么时候到达火车站吗？
It is important to know when to ask for help and understand why you need it.
重要的是要知道何时寻求帮助，明白你为何需要帮助。
All you have to do is to type in the address! Finally, a central computer system takes in all the information that it receives from the sensors and cameras and works out when to speed up, stop and turn.
你所要做的就是输入地址！最后，中央计算机系统会录入从传感器和摄像机接收到的所有信息，并计算出何时加速、停车、和转弯。
How do we know when to invest in an upgrade?
我们如何知道何时投资升级？
A driver takes the minibus to a certain place at a certain time, so people know when to expect it.
司机会在特定的时间开小型巴士去特定的地方，所以人们知道什么时候会有小型巴士来。
With these, however, arose the question of when to begin counting, and so, in the early 14th century, a number of systems evolved.
但是，随之而来的是何时开始计数的问题，因此，在14世纪早期，一些系统发生了变化。
This new calendar was ideal because it worked well for agricultural purposes as well as for knowing when to have traditional religious festivals.
这个新的日历是理想的，因为它的实用性很好，涵盖了农业活动以及传统宗教节日。
Auto manufacturers, for example, are trying to use tiny devices that can sense when to release an airbag and how to keep engines and breaks operating efficiently.
例如，汽车制造商正在尝试使用微型设备，这些设备能够感知何时释放安全气囊，以及如何保持引擎和刹车有效运转。
In America, people are faced with more and more decisions every day, whether it's picking one of thirty-one ice cream flavors, or deciding whether and when to get married.
在美国，人们每天都面临着越来越多的决定，无论是从31种冰淇淋口味中选择一种，还是决定是否结婚和何时结婚。
When we consider the nightly lifestyle of these bats, we will see they have to be sensitive to the changing light levels because this is how they sense when to start hunting.
当我们考虑这些蝙蝠的夜间生活方式时，我们会发现，它们必须对不断变化的光线水平保持敏感，因为这是它们感知何时开始狩猎的方式。
We've weighed so many decisions so carefully in raising our daughters—what school to send them to and what church to attend, when to give them cell phones, and with what precautions.
在抚养我们的女儿时，我们仔细权衡了许多决定——送她们上什么学校，上什么教堂，什么时候给她们手机，采取什么预防措施。
Who decides when to trigger a bailout?
谁来决定什么时候援助？
Deciding when to begin the HLD isn't easy.
决定何时开始HLD工作并不容易。
So knowing when to sell is of paramount importance.
因此，知道何时卖出头等重要。
Javier when to Spain to visit his boyfriend Samuel.
哈韦尔去西班牙看望他的男友塞缪尔。
So how will we know when to heed repugnance and when not?
那么，我们如何知道何时需要防止引起反感而何时则不必担心？
Overachievers know when to stop working and start playing.
杰出人士知道什么时候停止工作和开始玩耍。
Many developers also know when to use SAX and when to use the DOM API.
很多开发人员也知道何时使用SAX，何时使用DOMAPI。
Still, deciding when to end fiscal and monetary stimulus is tricky.
仍然，决定何时终止财政和货币刺激政策是辣手的。
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