The relative clause: it is defined as a clausal modifier, restrictive or non-restrictive, used to modify a preceding construction, most often a preceding noun or noun phrase.

• 关系分句，无论是限制性关系分句还是非限制性关系分句，都是用来修饰一个先行结构,而名词或名词词组是最常见的先行结构从句型修饰语。