▲简单地说，在英语句子中，两个结构关系密切或意义紧密相连的成分应紧挨在一起。但有时因为语法句型或修辞表达的原因，需要在这些紧密相连的成分之间插入一些其他词语，从而造成分隔现象（也叫“分裂现象”）。
语法结构的原因：
当两个及以上的后置定语同时修饰一个名词时，或两个及以上的状语同时修饰一个动词或形容词时，或一个及物动词有两个宾语时，分隔是必然的。
修辞表达的原因：
1. 为了让句子保持平衡、避免头重脚轻的现象，或者为了避免累赘而分隔。
2. 为使表达更准确、严密，以免引起误解而分隔。
3. 为了强调，可将句中某个成分置于句首或句尾，或为了使上下文衔接紧凑而把句中某个成分置于句首，或为了突出某一部分，从而造成分隔现象。
4. 避免句式呆板，使表达生动活泼。
▲同位语分隔举例：
1. There is a new problem involved in the popularity of private cars that road conditions need to be improved.
2. Information has been put forward at the meeting that more middle school graduates will be admitted into universitie
3. The question sometimes comes to my mind whether it was worth the effort.
4. There is no doubt, in my opinion, that what matters is not one’s looks, but one’s inner thoughts
Mr. Smith left word with his assistant that he had returned to his own country for winter holidays.
▲同位语分隔现象高考真题分析：
1. A story goes ________ Elizabeth I of England liked nothing more than being surrounded by clever and qualified noblemen at court. （上海卷）
A. when B. where C. what D. that
【解析】答案为D。句中的Elizabet I of England liked nothing more than being surrounded by clever and qualified noblemen at court.是主语a story的同位语。由于该同位语较长而谓语较短，为保持句子平衡，谓语动词goes放在了主语与同位语从句之间，造成同位语从句与主语的分隔。由此得知，引导一个陈述的同位语从句用that。
2. —It’s thirty years since we last met.
—But I still remember the story, believe it or not,________ we got lost on a rainy night.（四川卷）
A. which B. that C. what D. when
【解析】答案为B。此题“the story和其同位语从句that we got lost on a rainy night被插入语believe it or not分隔，在一定程度上影响了考生对句子结构的判断。
3. The news has come from the capital ________ an important meeting is to be held there.
A. where                     B. in which                    C. that                       D. which
【解析】此题很容易误选为A或B，原因是错把capital作为先行词，误选 where 或 in which在定语从句中作状语。而事实上，从句后面已经有状语 there。若选D，则 which 在从句中做何成分？从而可以排除。实际上，这是以that引导的同位语从句，修饰名词the news，选C。因为被has come from the capital 分隔，导致了同位语从句之间的分离，形成了干扰，使人容易误入陷阱。