Restrictive and Nonrestrictive Clauses

Adjective (relative) clauses can be restrictive clause or nonrestrictive clause. A restrictive clause limits the meaning of preceding noun or pronoun. A nonrestrictive clause tells us something about preceding noun or pronoun but does not limit the meaning of preceding noun or pronoun.

Example

•The student in the class who studied a lot passed the test. (restrictive clause)

•The student in the class, who had attended all the lectures, passed the test. (nonrestrictive clause)

In the first sentence the clause “who studied a lot” restrict information to preceding noun(student), it means that there is only one student in the class who studied a lot, hence it is a restrictive clause.

In the second sentence the clause “who had attended all the lectures” gives us information about preceding noun but does not limit this information to the preceding noun. It means there can be several other students in the class who had attended all the lectures.

A comma is always used before a restrictive clause in a sentence and also after nonrestrictive clause if it is within a main clause. “That” is usually used to introduce a restrictive clause while “which” is used to introduce a nonrestrictive clause.

Example
The table that costs $ 100 is made of steel. (restrictive clause)
The table, which costs $ 100, is made of steel. (nonrestrictive clause)

Adverb Clause

“ A dependent clause that functions as an adverb in a sentence is called adverb clause”
An adverb clause like an adverb modifies a verb, adjective clause or other adverb clause in a sentence. It modifies(describes) the situation in main clause in terms of “time, frequency (how often), cause and effect, contrast, condition, intensity (to what extent). ”

The subordinating conjunctions used for adverb clauses are as follows.

Time: when, whenever, since, until, before, after, while, as, by the time, as soon as
Cause and effect: because, since, now that, as long as, so, so that,
Contrast: although, even, whereas, while, though
Condition: if, unless, only if, whether or not, even if, providing or provided that, in case

Examples. Don’t gobefore he comes. He takes medicine because he is ill. Although he tried a lot, he couldn’t climb up the tree. Unless you study for the test, you can’t pass it. I will go to the school unless it rains. You are safe as long as you drive carefully. You can achieve anything provided that you struggle for it.