A clause is a group of related words that contains a subject and a verb. There are mainly 2 types of clauses, Independent Clauses and Dependent Clauses.
An independent (main) clause can stand alone as a complete sentence. A dependent (subordinate) clause cannot stand alone as a complete sentence. Lets take example of independent clause
He missed his train.
Notice here, these statements have subject and predicate. Grammatically complete statements like these are sentences and can stand alone. When they are part of longer sentences, they are referred to as independent (or main) clauses.
Swimming, which is a very good exercise,is suitable for people of all ages.
which is a very good exercise in sentence (1) and Because he overslept,in sentence (2) are dependent clauses.
Functions of Dependent Clauses
As with phrases, dependent clauses fulfill different functions within sentences. They can be classified as adjectival (relative), adverbial, nominal (noun).
An adjective clause is a dependent clause that modifies a noun or a pronoun.
An adjectival clause usually begins with one of the relative pronouns: which, what, whatever, who, whose, whom, whoever, whomever, or that.
It may also begin with a relative adverb: when, where, before, since, or why.
The adjective clause will follow one of these two patterns:
Relative pronoun or adverb + subject + verb
Relative pronoun as subject + verb
Adjectival Clauses Beginning with a Relative Pronoun:
We hired those who came with the strongest recommendations.
The child you saw in the magazine is my youngest sister.
Adjectival Clauses Beginning with a Relative Adverb:
Did Fred tell you the reason why he was late for work this morning?
I remember when my sister was a baby.
NOTE : Do not use commas in any of the completed sentences.
An adverbial clause is a clause that functions as an adverb. In other words, it contains subject and predicate, and it modifies a verb.
Adverbial clauses always begin with a subordinating conjunction. Common subordinating conjunctions include: as, as if, as soon as, as though, because, before, even if, even though, if, if only, in order that, now that, once, and rather than.
Unlike adjectival clauses, adverbial clauses can be separated from the word they describe.
Adverbial clauses can be placed at the beginning, middle, or end of a sentence. If the clause is placed at the beginning or middle of a sentence, it is often set off by commas.
Since the guests were so convivial,I soon forgot my troubles.
Did you visit the Statue of Liberty when you were in New York?
I decided, after I lost an especially important file, to make two backup copies of key documents.
A nominal, or noun, clause is a subordinate clause that acts as a noun.
Noun clauses can function as subjects, objects, and complements within sentences. They begin either with a relative pronoun or with a word such as how, why, where, when, if, or whether.
Noun clauses can be difficult to identify, because a noun clause can be a subject of a verb, object of a verb, subject complement , object of a preposition, adjective complement.
Correct: Do you know what time it is?
Incorrect:Do you know what time is it?
Correct : Everybody wondered where Billy went
Incorrect:Everybody wondered where did Billy go
1)Whatever you do is your business.
2)Whatever is in the box is a mystery.
3)Can you tell me what he is doing?
4)She doesn't understand why he is leaving.
1)What he said was obvious to me.
2)The children who are on the bus are going to visit the museum.
1)I saw Joe when I went to the store.
2)He sat quietly in order to appear polite.
3)The group of tourists decided to have lunch in the village.