If clauses are usually used to talk about uncertain events and situations. They often refer to a condition – something which must happen first, so that something else can happen.
- If you love me, I will love you.
- If you study well, you will pass the exam.
- If you marry me, I will make you my queen.
- If you don’t hurry up, you will be late.
Clauses of this kind are often called conditional clauses. There are four main types of conditional clauses in English. They are:
- Zero conditional
- Type 1 conditional
- Type 2 conditional
- Type 3 conditional
Position of an if clause
An if-clause can come at the beginning or end of a sentence. When an if-clause begins a sentence, we use a comma to separate it from the rest of the sentence.
- I will phone you if I have time.
- If I have time, I will phone you.
Leaving out If
In a formal or literary style if can be dropped and an auxiliary verb put before the subject. This is common with had, should and were.
- Were I you I would accept the offer. (= If I were you I would accept the offer.)
- Had he not received her help he wouldn’t have become a millionaire. (= If he had not received…)