Introduction & Types: Clauses

Clauses

A clause is a group of words that contains at least a subject and a verb. A clause can stand alone as a complete sentence (an independent clause) or function as part of a sentence (a subordinate clause). Subordinate clauses cannot stand alone and depend on a main clause to complete their meaning.

There are three main types of subordinate clauses:

• Noun clause
• Adverbial clause
• Relative clause (adjective clause)

Noun Clause

A noun clause is a subordinate clause that functions like a noun or noun phrase in a sentence. It can act as subject, object, complement, object of a preposition, etc. Noun clauses often begin with pronouns, adverbs or conjunctions.

Read these sentences and notice the noun clauses (underlined here):

• I hope that I shall pass. - the clause that I shall pass is a noun clause functioning as the object of hope.
• She knows what I want. - the clause what I want is a noun clause functioning as the object of knows.

Noun clauses commonly start with:

• Pronouns: what, which, who, whom, whose
• Adverbs: when, where, why, how
• Conjunctions: if, that, whether

More examples of noun clauses:

• You can see what we have done.
• Can you tell me who has done it?
• Do you know whose car it is?
• I don't know which book he has bought.
• I can't say whom I should believe.
• I can't tell you when he will come.
• Please tell me why he is always late.
• I don't know where he has gone.
• Does anyone know how it has happened?
• I wonder if the weather is going to be all right.
• She asked whether the train would leave on time.
• I can tell you that he is a good boy.

Functions of Noun Clauses

As Subject

• What you said surprised me.
• When she comes is uncertain. (corrected from "When she comes is uncertain.")
• Whether he will help you will be known soon.
• That he would come seemed unlikely. (corrected)
• How he crossed the border is a mystery.
• Why he came here is still unknown to us.

As Object

• He says that he will help me.
• She couldn't decide what she should do.
• You must learn when you should speak.
• She wondered whether she should stay any more.
• I don't know who gave him this advice.
• Have you decided where you will go for your holidays?
• I asked him how I could reach that village.
• I don't know why he sold his house.

As Complement

• Our belief is that he will help us.
• This is where she works.
• My worry is why he should behave like that.
• This is what you are looking for.
• The problem is how we can cross this river.

As Object of a Preposition

• You should pay attention to what the teacher says.
• There is no complaint except that he comes late.
• There is no meaning in what he says.
• No one is aware of how he has opened the lock.
• Everything depends on whether he helps us or not.
• It was difficult to decide on where we should go for help.
• They couldn't agree about who should do the work.

As Complement of an Adjective

• I am not sure where he has gone.
• They are confident that they will find the thief.
• It is doubtful whether she will reach in time.

As Object of an Infinitive

• She wants to know what is going on here.
• He came to see that he was mistaken.
• She wanted to ask if I could help her.

In Apposition to a Noun (Noun + Noun clause)

• The rumour that he was killed is true.
• We should pursue the idea that we should set up a factory.
• The fact that he has failed surprised his parents.

As Object of a Participle

• Thinking that he would die, they took him to a hospital.
• Hoping that they would win, they felt overjoyed.

Adverbial Clauses of Condition

An adverbial clause of condition expresses a condition and is introduced by if, unless, whether, or other conjunctions. It is a subordinate clause and modifies the main clause (often indicating when or under what condition something will happen).

Examples:

• If you run fast, you will catch the train.
• Unless you work hard, you will not pass.

Types and their tense patterns

(i) If the if-clause refers to a likely or possible future situation, use the simple present in the if-clause and will/shall/can/may in the main clause:

• If it rains, we'll go indoors.
• If she works hard, she will pass.
• If you request me, I shall help you.
• If you need a pen, you can take mine.
• If you want to get good marks, you must work harder.

(ii) If the if-clause refers to a general truth or a condition that always has the same result, use the simple present in both clauses:

• If the engine gets too hot, it starts to smoke.
• If you heat ice, it melts.
• If you boil water, it evaporates.
• If you beat a child, he weeps.

(iii) If the if-clause refers to an unlikely or hypothetical present or future situation, use the simple past in the if-clause and would/could/might + base verb in the main clause:

• If you ran fast, you might catch the train.
• If I won a lottery, I would buy a car.
• I would tell you if I knew the answer.
• If a thief entered your house, what would you do?
• If I were rich, I would open a school for the poor.

(iv) If the if-clause refers to a situation that did not happen in the past, use past perfect in the if-clause and would have/should have/could have/might have + past participle in the main clause:

• If she had worked hard, she would have passed. (She didn't work hard, so she didn't pass.)
• If he had left early, he might have caught the train.
• If he had informed me, I would have received him at the railway station.

When the main clause refers to the present result of a past unreal condition, use past perfect in the if-clause and would/could/might + base verb in the main clause:

• If you had followed my advice, we would be home by now.

(v) For an unlikely future situation, we can sometimes use were to or should + infinitive instead of the simple past:

• If you should meet him, tell him to come here.
• If she were to die before you, who would look after your children?
• If you need any help, ring me up.

(vi) If only expresses a wish referring to present or future time:

• If only I were rich.
• If only I could swim.
• If only I knew her name.

(vii) If only can also express a wish about the past:

• If only he had remembered to post that letter.
• If only I had met her.
• If only he had spoken the truth.

Adverbial Clauses of Time

Adverbial clauses of time tell us when something happens. Common subordinating conjunctions are after, before, since, when, while, whenever, till/until, as, once, as soon as, no sooner... than, hardly... when/before.

Examples:

• I arrived after he had started.
• The patient had died before the doctor arrived.
• I have never seen her since she was ten years old.
• His father died when he was young.
• Someone called while you were out.
• Whenever I smiled, she smiled back.
• I will wait here until you return.
• As I was leaving, the phone rang.

Tense rules and special constructions

• When the time clause refers to the present or past, the verb in the time clause uses the same tense it would in a main clause: She was standing by the door when I heard her speak.
• For an event in a time clause that will occur before an event in the main clause, use the present perfect in the time clause: When you have taken your lunch, come to me.
• Use when, while, as for circumstances in which something happens: The doors open when I press this button.
• Use when, after, once to show one event following another: Once the damage is done, it takes many years for the system to recover.
• Use as soon as for one event happening after a very short time: They heard a loud explosion as soon as they entered the house.
• With no sooner the pair is no sooner ... than: No sooner had he arrived than he had to leave again.
• With hardly the pair is hardly ... when/before: Hardly had he entered the house when the phone rang.
• Use till/until to indicate that a situation continued up to a point: I waited until she came back.
• Use since to indicate a situation that began at a particular time and continues to the present: I have not met her since she was a child.

Relative Clauses

A relative clause (also called an adjective clause) modifies a noun or pronoun. It is placed immediately after the noun it describes. Relative clauses give essential information (defining) or additional information (non-defining).

Examples:

• The boy who came into the house was my friend.
• The house which our neighbour bought is made of stone.
• Anwar, who returned yesterday, will come to meet us. (non-defining)

Defining vs Non-defining relative clauses

• Defining clauses (restrictive): give essential information; they are not separated by commas. The relative pronoun may sometimes be omitted (except when it is the subject of the relative clause).
• Non-defining clauses (non-restrictive): give extra information about the noun; they are set off by commas and the relative pronoun cannot be omitted.

General rules about relative clauses and pronouns

• In a non-defining clause use commas. Example: Satish, who you met yesterday, is a friend of mine. (Here the relative pronoun cannot be omitted.)
• In a defining clause the relative pronoun can sometimes be omitted when it is not the subject: The woman you met yesterday is my mother. (Here the relative pronoun is omitted.)
• You cannot omit the pronoun when it is the subject of the relative clause: The boy who gave you this book is my friend.
• In non-defining clauses, prepositions are usually placed before the relative pronoun: This is Mohan, about whom I was talking.
• In defining clauses, it is common to place the preposition at the end of the clause in informal style: This is the boy I was talking about.
• The pronoun that is used only in defining clauses; who, whom, whose, which can be used in defining and non-defining clauses (subject to other rules).
• Relative adverbs where, when, why can introduce clauses referring to place, time and reason respectively: This is the house where we lived.

Relative Adverbs

The relative adverbs when, where, why can replace a preposition + relative pronoun:

• When replaces in/on which: That was the year when this city was flooded.
• Where replaces in/at which: This is the house where he lived.
• Why replaces for which: This is the reason why he was fined.

Use of Pronouns for Persons

(i) Nominative case: Use who or that. That is often used after superlatives and after words like all, nobody, someone when either who or that is possible.

• This is the best that I could have done in that situation.
• The girl who cheated you is called Romola.
• The policeman who arrested the thief has white hair.
• All who/that listened to his speech praised him.

(ii) Objective case: Use whom, who, or that. Whom is more formal; in speech people often use who or omit the pronoun:

• The boy whom/who I met is called Ramesh. - Or: The boy that I met is called Ramesh. - Or: The boy I met is called Ramesh.

(iii) With prepositions: Use whom or that with the preposition before the pronoun in formal style: The boy to whom I was speaking is my neighbour. Informally the preposition often moves to the end: The man who/whom I gave it to was a foreigner.

(iv) Possessive: Use whose: Boys whose result has not been declared can meet the principal.

Use of Pronouns for Things

(i) Nominative case: Use which or that (which is more formal):

• This is the pen which/that cost me $5.
• This is the house which/that has been sold.

(ii) Objective case: Use which, that, or omit the relative pronoun:

• The pen which/that I bought yesterday was beautiful.
• The pen I bought yesterday was beautiful.
• All the mangoes that fall are eaten by children.
• This is the best place (that) I have ever seen.

(iii) With prepositions: Place the preposition before which in formal style: The chair on which I was sitting was made of teak wood. Informally: The chair I was sitting on was made of teak wood.

(iv) Possessive: Use whose or of which: My house, whose walls are made of stone, faces east.

Note: The pronoun which can also refer to a whole sentence: I bought this compass, which helped me a lot.

Summary and Usage Tips

• Identify whether the clause acts like a noun, adverb or adjective to decide if it is a noun clause, adverbial clause, or relative clause.
• Remember that noun clauses often begin with question words (what, who, whom, which, whose, when, where, why, how) or with conjunctions (that, if, whether).
• For conditional adverbial clauses, follow the tense patterns: present → future; past → would/could/might; past perfect → would have/could have/might have.
• Use commas to separate non-defining relative clauses and do not omit the relative pronoun in them.
• Use who/whom/that for persons and which/that for things, bearing in mind formal vs informal styles and case (subject/object/possessive).

If you practise identifying clauses in sentences and then rewriting sentences using different clause types, your understanding and accuracy will improve quickly. Try converting direct statements into noun clauses (e.g., "He said, 'I am tired.'" → "He said that he was tired.") and practising conditional sentences and relative clauses with and without commas.