And when we're talking about the amplitude of the wave, we're talking about the deviation from that average level. So, if we define the average level as zero, you can have either a positive amplitude or a negative amplitude.

当我们讨论一个波的振幅时,我们说的是偏离平均位置的量,如果我们把平均位置,定义为零的话，那幅值不是,正的就是负的，有时候人们在。

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It is also more than one standard deviation below the historical average of 30%, making this an unusually low reading.

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Nonetheless, optimism remains more than one standard deviation above its historic average of 39%-a sign that it remains at high levels.

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Pessimism not only stayed at its lowest level since December 23, 2010, it also remained at a reading that is more than one standard deviation below the historical average of 30%.

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