Non-restrictive attributive clause: equivalent to an parenthesis or an explanation of the antecedent, with only a loose relationship with the antecedent. Comma is often used to separate from the main clause in the text. In fact, its usage is very similar to that of restrictive attributive clauses, but it cannot be used as a modifier.
There are four major differences between restrictive attributive clauses and non-restrictive attributive clauses, which are briefly introduced:
First of all, the roles in sentences are different.
The restrictive attributive clause has a restrictive effect on the modified antecedent, making the meaning of the word more specific and clear. Restrictive attributive clauses cannot be omitted, otherwise the meaning of the sentence will be incomplete.
Non-restrictive attributive clauses are not closely related to antecedents, but only some additional explanations are given, which do not play a limiting role. If the non-restrictive attributive clause is omitted, the meaning of the main clause is still complete.
Second, the external manifestations are different.
Restrictive attributive clauses are closely related to antecedents and cannot be separated from main clauses by commas. Non-restrictive attributive clauses are not closely related to antecedents, so they can be separated from the main clause by commas.
Third, the antecedents are different in content.
The antecedent of most restrictive and non-restrictive attributive clauses is often a word or phrase, and in special cases, the antecedent of non-restrictive attributive clauses can also be the whole main clause. In this case, which guide is often taken by non-restrictive attributive clauses?
Fourth, the use of relative words is different.
That can't be used to guide non-restrictive attributive clauses. All relative pronouns and adverbs can guide restrictive attributive clauses. Most relative pronouns and adverbs can guide non-restrictive attributive clauses, but that can't.