规则7 在独立子句后用冒号引出并列项、同位语、补充说明或举例引文[rule-7]

冒号告诉读者，后面的内容与前面的子句密切相关。冒号的作用比逗号强，分隔的力量比分号弱，比破折号更为正式。它通常跟在独立子句之后，不应把动词与其补语分开，也不应把介词与其宾语分开。下面左栏的例子是错误的；它们应当像右栏那样改写。

误：Your dedicated whittler requires: a knife, a piece of wood, and a back porch.
正：Your dedicated whittler requires three props: a knife, a piece of wood, and a back porch.

误：Understanding is that penetrating quality of knowledge that grows from: theory, practice, conviction, assertion, error, and humiliation.
正：Understanding is that penetrating quality of knowledge that grows from theory, practice, conviction, assertion, error, and humiliation.

如果第二个独立子句解释或补充第一个，就用冒号把它们连接起来。

But even so, there was a directness and dispatch about animal burial: there was no stopover in the undertaker's foul parlor, no wreath or spray.

冒号可以引出一段支持或补足前面子句的引文。

The squalor of the streets reminded her of a line from Oscar Wilde: "We are all in the gutter, but some of us are looking at the stars."

冒号还具有某些形式上的功能：跟在正式信函的称呼之后，把时间记法中的小时与分钟分开，以及把作品的标题与其副标题分开，或把《圣经》的章与节分开。