同位语一般置于本位语之后，可以不用标点符号隔开，也可以用逗号、冒号或破折号隔开，
例如：The thought came to him that maybe the enemy had fled the city.
这里thought就和它的由that引导的同位语从句被谓语部分came to him所分割。
同位语从句。
一个名词或代词后面有时可跟一个分句，对前者做进一步解释，说明它指的是谁或是什么等，这叫同位语。名词做同位语的情况最多，当然也有较复杂的结构。
例如：
We communists seek not official posts，but revolution.
The lay out plan was completed within three months，half the usual time.
Wei Fang，normally a timid girl，argued heatedly with them about it.
