Normally this material is invisible, but some of it can be seen in silhouette against the nebular background, as long dust lanes and a small, dark, elliptical-shaped knot.
平时，我们是看不见这些物质的，但是，我们通过星云这个背景可以看见它的一部分，它就像是一条长长的灰尘组成的细线，或者是一个一个很小的椭圆形的结。
The heterogenous 8-shaped knot is formed by changing one of two X-shaped cross structures at the middle part of the standardized 8-shaped knot into Chinese doughnut-shaped twisted structure.
异型8字结是将规范的8字结中部的两个X形交叉结构中的一 个，变换成麻花状绞纽结构的一种结扣形式。
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