The students lined up in the streets to vote for the presidential candidates--they were each over the age of eighteen.
但是除此之外，我们还有必须了解的一点，来看看这个关于破折号的说明：The first thing to know when talking about dashes is that they are almost never required by the laws of grammar and punctuation. 破折号基本不受语法和标点规则的限制。
举个例子，前面我们提到的分号，冒号，句号，在连接句子时，都不可以再跟另一个连词放在一起用了。比如：The exhibits have proved very popular; and, in fact, more than a million wishes have been written over the past ten years. 这句话就是错的，因为连接句子时，既用了分号，又用了连词，功能重复了。但是，破折号就很特殊，它可以搭配连词一起来用。