Making sure your colour is set to black (if it's not, click on the top colour square and change this 100% black) and select your brush tool.

确认你的前景色为黑色(如果不是，单击前景色方框，然后改成100%黑)，选择画笔工具。

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The photos at the top of each summary add colour, but they suggest an obligation to aesthetics more than the fulfilment of any sort of function.

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The crowns on his top teeth are a completely different colour from his own teeth in his bottom jaw.

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The capsules are arranged as pixels and electric charges applied to each pixel pull either the black or the white particles towards the top of the capsule (and the opposite colour to the bottom).

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