If you don't shake the black card, it will leave a very clear line on your photo.

若不晃动黑卡，影像中会留下一条很明显的直线。

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A black card is just a regular cardboard paper. The key point is the color black. Black absorbs light. Therefore, the camera will not capture the black card.

黑卡，就是一般的纸，重点是要黑色，黑色会吸光，如此相机才不会拍摄出这片卡的颜色。

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In the diagram, a thick blue arrow stands for page transition, a black arrow stands for card invocation, and an orange dotted arrow stands for field reference.

在图中，蓝色的宽箭头表示页面转换，黑色箭头表示卡片调用，而桔红色虚线箭头则表示字段引用。

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The black card he just went off and built it.

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