It is important to add only the amount of black drop needed. Side and bottom masking determined by the amount of black drop and image size.

如果需要的话，应该增加黑滴的数量，这点很重要。侧部和底部遮蔽是由黑滴数量和图像尺寸决定的。

youdao

When you see the black arrow display on the left of the edge and the narrow bounding rectangle, as shown in figure 8, drop the component.

如图8所示，当看到左边缘上显示黑色箭头，并伴有狭长的外接矩形时，放下该组件。

youdao

Drop it onto the layout (the black border indicates where and what size the portlet will be when you drop it).

将它拖到这个布局上(黑色加粗边框表明您释放时的位置和尺寸大小)。

youdao

They concluded that the black drop results from blurring of the image (whether from Earth's atmosphere, or inevitable imperfections of the telescope) combined with the way that the disc of the sun fades in brightness towards its rim.

ECONOMIST: Transits of Venus

The 23% Black Monday drop in 1987 left a divot that was quickly filled in.

FORBES: Magazine Article

There is also historical research to be done: for instance, what causes that meddlesome black-drop effect?

ECONOMIST: Transits of Venus