known structure

• 已知结构

known structure的用法和样例：

例句

1. This image from the Hubble Space Telescope reveals the Cat&squots Eye Nebula to be one of the most complex planetary nebulae known.
   这张来自哈伯太空望远镜的影像，透露出猫眼星云是现知结构最复杂的行星状星云之一。