VARIOUS STRUCTURES WITH IF
1. If with happen to : "Happen to" is used to suggest that something happens by chance . It is often used with If .
If you happen to pass a baker's , pick me up a loaf , would you ?
"should happen to" can be used together.
If you should happen to finish early , give me a ring .
2. If so and If not : These are two useful expressions which are used instead of complete sentences .
Have you got a free evening next week ? If so , let's have dinner .(=If you have , let's ... )
Is anybody feeling cold ? If not , let's put the central heating off .
3. If I'd have : In Informal spoken English , an extra have is sometimes put into if-clauses referring to the past
This is considered "incorrect" and is not normally written , but it is common even in educated people's speech .
If I'd have known I'd have told you . (=If I had known ....)
4. If meaning Although : In a rather formal style of English , "if" can be used with a similar meaning to (al)though . This is most common in the structure If + adjective ( with no verb ) . "If" does not give so much importance as (all)though to the contrast , exception or concession that is referred to .
His style , if mannered , is pleasant to read .
The profits , if a little lower than last year's , are still extremely healthy .