If you don't understand how the formula works and the principle behind it, it can often be very difficult to use the formula.

如果你不理解这些公式如何运作已经公式背后的原理，你将会很难利用这些公式。

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Finally, let us take a look at another valuable feature that is often never used but once you learn how to use it, you will never forget it.

最后我们来了解另一个非常有用的功能，你有可能从来不会用，但一学会就无法忘记。

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Pull out the highball glass or wineglass you use most often, and measure how much it holds.

拿出你最常使用的酒杯，测测看它可以盛多少酒。

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You might have a coffee maker with a frothing spout for making fancy dirks, but how often do you use it?

FORBES: The Rolex of Coffee Makers - How Swiss-Made Precision Changed My Life