A pseudo column is an identifier with a predefined name that holds information about the hierarchical query and that can be used like any column in a table.
伪列是具有预先定义的名称的标识符，其中包含关于分级查询的信息；它的用途类似于表中的任何列。
2
Designated by a colon preceding the name, pseudo-classes are independent of particular elements and instead look at what's happening within the document.
伪类的表示方法是在名称前面加一个冒号。伪类与特定元素无关，而是根据文档中发生的情况应用样式。
3
Pseudo-time travel like this happens every day, with pictures taken by the Hubble Space Telescope, the mammoth Keck telescopes in Hawaii and the Chandra X-ray Observatory satellite to name just a few.