conditional sentences

CONDITIONAL SENTENCES


A. WHAT IS CONDITIONAL SENTENCE?
Conditional Sentence is a sentence that indicates that an action or a condition is completed only if the condition given is fulfilled. Conditional Sentences are also known as Conditional Clauses or If Clauses. They are used to express that the action in the main clause (without if) can only take place if a certain condition (in the clause with if) is fulfilled.
Conditional sentences have two parts: the if-clause and the main clause. In the sentence If it rains, I will stay at home, "if it rains" is the if-clause, and "I will stay at home" is the main clause.


B. TYPES OF CONDITIONAL SENTENCES
There are 4 types of conditional sentences according to the degree of probability that they express.

1. Zero Conditional (type 0)
The zero conditional is a structure used for talking about general truths, or scientific facts_ things which always happen under certain conditions. The verb in the if-clause is in the present tense; the verb in the main clause is in the present tense too.
If-clause ~ Present Tense
Main Clause ~ Present Tense

Formula
IF + DOES, DOES
If + Simple Present Tense, Simple Present Tense

Examples
- If you heat water to 100°C, it boils.
- If you pour oil into water, it floats.
- If you are tired, go to bed!

Used
1. Talk about universal truth.
Example: If you heat ice, it turns to water.
2. To give commands
Example: If you are tired, go to bed!
3. To state general rules
Example: If we heat water enough, it begins to boil.
In statements like that, if means the same as when or every time.


2. First Conditionals (type 1)
The first conditional (also called conditional type 1) is a structure used for talking about possibilities in the present or in the future.
The verb in the if-clause is in the present tense; the verb in the main clause is in the future simple. It doesn't matter which comes first. There is usually a comma between the two clauses.
If-clause ~ Present Tense
Main Clause ~ Future Tense

Formula
IF + DOES, WILL DO
If + Present + Future

Examples
- If I feel sick tomorrow, I will not go to school.
- If it rains, the match will be cancelled.
- If I have the money, I will buy this car.
- If it is sunny, we'll go to the park.
- Peter will be sad if Susan leaves.
- If you cook dinner, I'll wash the dishes.

Used
1. To speaks about possible or probable future events.
If I feel sick tomorrow, I will not go to school..
2. To make promises or warnings
If you forget my birthday, I’ll never speak to you again.


3. Second Conditionals ( type 2)
The second conditional (also called conditional type 2) is a structure used for talking about unreal situations in the present or in the future.
The verb in the if-clause is in the past tense; the verb in the main clause is in the conditional tense.
If-clause ~ Past Tense
Main Clause ~ would + an infinitive

Formula
IF + DID, WOULD DO
If + past tense, would + infinitive

Examples
- If we were birds, we would fly in the sky. (Only wish in future)
- Were I you, I would not attend the meeting.
- If he were the Prime-Minister of India, he would abolish untouchability from the country.
- If you studied hard, you would stand first.
- The people will respect us, if we respect them.

Used
1. To speak about present and future situations which are unlikely to happen.
If I were you I wouldn't do this.
2. When the supposition is contrary to known facts
If I lived in New York, I wouldn't have to commute there each day. (But I don't live in New York.)


4. Third Conditionals (type 3)
The third conditional (also called conditional type 3) is a structure used for talking about unreal situations in the past. In other words, it is used to talk about things which DID NOT HAPPEN in the past.
If-clause ~ Past Perfect Tense
Main Clause ~ Would Have + Past Participle

Formula
IF + HAD DONE, WOULD + HAVE DONE
If + Past Perfect Tense, Would + Present Perfect

Examples
- If I had studied harder, I probably would have passed the exam.
- If I had had enough money, I would have bought the camera yesterday.
- If you had driven more carefully, you would not have had an accident.
- If we had played a little better, we could have won the game.
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Used
1. To speak about impossible past events.
If they’d gone by bus, they would have arrived much later. (They didn’t go by bus).

C. I WISH / IF ONLY
1. We use wish and if only +past simple/continuous or could when we want a situation or thing in the present to be different or to change.
The time of the action referred to in the subordinate clause is the same as the time of making the wish.
Examples
- He wishes that he were rich.
- I wish I didn’t have to leave.
- I wish he was waiting for me.
- I wish I could help you.
2. We use wish + would to complain about a thing or a situation.
Examples
- She wishes that you would come to the meeting tomorrow.
- I wish you wouldn’t be so rude.
- I wish my mother would let me go out till late.
- She wishes her child would sleep all night long.

2. We use wish / if only + past perfect / continuous or could have + p.p. to express a wish about the past.

Examples
- They wish that they had studied harder when they were young. (they didn’t study)
- I wish I hadn’t failed the exam. (I failed the exam