Non-defining relative clauses add extra information to sentences.

非限定性定语从句给句子增加了额外的信息。

Relative clauses add extra information to a sentence by defining a noun. They are usually divided into two types –defining relative clauses and non-defining relative clauses.

定语从句是对句子里的名词加入额外的信息。一般来讲，有两种类型的定语从句—限定性定语从句和非限定性定语从句。

Separate appositives (a noun, or noun phrase) or non-defining relative clauses.

单独的同位语（名词或名词短语）或不明确的关系从句。

Remember that defining relative clauses are used to add important information. The sentence would have a different meaning without the defining relative clause.

请记住，限定性定语从句是给句子增加了重要的信息，句子如果没有了定语从句，其意义不同。