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。

youdao

This represents a relationship between these two elements that is independent of the main hierarchy.

这表示这两个与主层次结构无关的元素之间的关系。

youdao

These include MXML elements and attributes which values are independent of the specific SOAP binding settings.

这些包括了 MXML 元素和相应的属性，这些属性的值不依赖于专门的 SOAP 绑定设置。

youdao

These elements seemed independent of one another.

NEWYORKER: History of a Disturbance

At the same time, ObamaCare increases the costs that a physician faces by continuing to run her own independent medical practice (with elements such as mandates to install costly electronic record keeping).

FORBES: Hospitals Are Going On A Doctor Buying Binge, And It Is Likely To End Badly

The Independent Police Complaints Commission is conducting inquiries into two elements of the case.

BBC: 'I wish Raoul Moat was alive,' says victim's sister