Clauses are the building blocks of the English language. Any sentence hat you write which has a subject (the doer of the action) and a verb (an action word) is called a clause. Whereas a phrase is a group of words which makes sense but not complete sense, a clause makes complete sense.

For example, "a clear blue sky" (is a phrase) and "A clear blue sky welcomed me in Leh" (is a clause-The subject is 'A clear blue sky' and the verb is 'welcomed').

1) Principal or Main Clause
A main clause is a clause that contains a subject and an object. They make sense on their own.
For example,

• "I like ice-cream" is a simple sentence made of a main clause.
• "I like ice-cream and I like chocolate" is a compound sentence made up of two main clauses ('I like ice-   cream' and 'I like chocolate'). The two main clauses are joined by the conjunction 'and.'

2) Subordinate Clause
A subordinate clause contains a subject and a verb but it depends on the main clause for making sense as it does not make complete sense on its own. 
For example, "I will go to the market if you come with me" is a complex sentence. It has a main clause 'I will go to the market' and a subordinate clause 'if you come with me'. The main clause 'I will go to the market' makes complete sense on its own. But, the subordinate clause 'if you come with me' does not make complete sense on its own and depends on the main clause for its complete meaning.

Based on the function they perform in the sentence, clauses can be categorized as:
•    Noun Clause- is a group of words which contains a Subject and Predicate of its own, and does the work of a noun. For example, "I like what I see" as a way of saying "I like cakes". The highlighted portion is a clause that is functioning as noun.

•    Adjective Clause-usually comes after the noun it qualifies and is made up of several words which, like all clauses, will include a subject and a verb.It answers the adjective questions 'What kind? How many? or Which one?" For example, "The umbrella which has a broken handle is mine."The highlighted portion is a clause that is functioning as an adjective.

•    Adverb Clause-is a group of words which contains a Subject and Predicate of its own, and does the work of an adverb. It answers the adverb questions How? When? Where? Or Why? For example, "You may sit wherever you like." The highlighted portion is a clause that is functioning as an adverb

 Identify the clauses and point it whether it is a Noun Clause, Adjective Clause, Adverb Clause.

a.The bankers need to know what they should do.

b. The books, which are lost, are not really necessary.

c. Whether you like it or not, you have to go to bed now.

d. Students who are intelligent get good grades.

e. No one knows he is.

f. When I was younger, I thought so.

g. He laughs best who laughs last.

h. I went to see what had happened.

i. He met a girl whose eyes were blue.

j. I shall remain where I am.

Read More : Difficult Reading Comprehension Passages

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