A conditional sentence must have at least two clauses: a conditional clause and a result clause. The conditional clause usually states a condition and the result clause states what will happen if the condition is fulfilled.
Read the sentences given below:
If you come tomorrow, I will tell you a secret.
Here the clause ‘If you come tomorrow’ expresses a condition. It is therefore called a conditional clause. Note that conditional clauses usually begin with if or unless.
The clause ‘I will tell you a secret’ states what will happen if the condition mentioned in the conditional clause is met. It is therefore called the result clause.
Position of If clauses
The result clause and the if clause are interchangeable in position.
Susie will buy a car if she gets a promotion. OR If she gets a promotion, Susie will buy a car.
Note that when an if clause comes at the beginning of a sentence, it is usually separated from the rest of the sentence by a comma.
There are three main types of conditional clauses and they are easily distinguished by the tenses used in them.
Type 1 conditional (real condition)
Here we use a simple present tense in the if clause and a simple future tense in the result clause.
He will come if you invite him.
He will win if he works hard.
She will help if you ask her.
I will speak to him if you want.
The type 1 conditional sentences merely state that something will happen if a certain condition is fulfilled – and the condition is nothing impossible or improbable.
Type 2 conditional (unreal or imaginary condition)
Here we use a simple past tense in the if clause and would + infinitive in the result clause. Note that the auxiliaries should and could are also used.
He would come if you invited him.
The type 2 conditional sentences state the probable result of an imaginary condition. The possibility of ‘your inviting him’ and ‘his coming’ is more doubtful here than in a sentence in the type 1 conditional.
More examples are given below:
He would win if he worked hard.
She would help if you asked her.
I would speak to him if you wanted.
I would do it if it were possible.
If he was twenty years younger, he could perhaps do it.
The type 2 conditional sentences are sometimes used to give advice.
If I were you I would accept this offer.
If I were you I wouldn’t provoke the old man.
Note the use of were instead of was.