Now in a new layer above the watercolor layer, and drawing straight up, make a Linear Gradient going from black to transparency so that afterwards your canvas basically fades to black down the bottom.

现在在水彩图层之上再新建一个图层，然后从下至上从黑色到透明做线性递减绘制，这样基本上整个画布到底部就褪化为黑色了。

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There is a social gradient in health that runs from top to bottom of the socioeconomic spectrum.

健康方面的社会梯度从社会经济状况的顶端延伸到底部。

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Using the gradient Tool (g) with a Black to 0% opacity gradient, click and drag a gradient from the bottom up into the planet for the bottom and from the top down for the top of the planet.

使用渐变工具，设置黑色到0%不透明的渐变，从画布底部向上点击拖拉渐变到行星位置，然后，从画布顶部点击拖拉渐变到行星顶端。

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