Page 258 - Oxford_English_Grammar_Course_Basic_2015

SECTION 18 if *H—
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grammar summary

Mo s t t e n s e s are possible in sentences with if.
He won't come tomorrow if he came yesterday.
If that was Mary, why didn't she stop and say hello?
If you've been to Paris, you've seen the Eiffel Tower.
Oil floats if you pour it on water.
If you're happy, I'm happy.

Note the following th r e e i m p o r t a n t s t r u c t u r e s :

• p r e s e n t t e n s e s f o r f u t u r e :
With if, we use pr e s e n t tenses to talk about the future.
I'll phone you if I have time. (NOT... if I will have time.)

• if+ pa s t , ... would...
We can use pa s t tenses with if to show that something is no t r e a l or no t pr o b a b l e n o w .
(We normally use would in the other part of the sentence.)
If I had more money, I would buy a car now.
• if+ pa s t p e r f e c t ,... would have...
To talk about un r e a l p a s t events - things that did not happen - we use if+ pa s t p e r f e c t .
(We normally use would have + pa s t p a r t i c i p l e in the other part of the sentence.)
I'm sorry you had all those problems. If you had asked me, I would have helped you.

These three structures are often called'first','second'and'third conditional'.
The structure with two present tenses (e.g. If you're happy, I'm happy) is sometimes called
'zero conditional', for no very good reason.

We can use unless to mean 'if not','except if'.
You can't come in unless you have a ticket. (=' if you don't have a ticket.')

If you were the only girl in the world, If you can keep your head when all about you
and I were the only boy . . . are losing theirs,... you’ll be a man, my son.

(Song by Clifford Grey, British songwriter, born 1937) (Rudyard Kipling, British short-story writer, novelist
and poet, 1865-1936)

If you can find something that everyone If you can keep your head when all about you are
agrees on, it’s wrong. losing theirs, you just don’t know what’s going on.

(Mo Udall, American politician, 1922-1998) (British Army saying)

If God did not exist, it would be necessary to
invent him. If one morning I walked on top of the water

(Voltaire, French writer, 1694-1788) across the Potomac River, the headline that
afternoon would read “President Can’t Swim”.
(Lyndon B. Johnson, American politician, 1908-1973
If the automobile had followed the same - President 1963-1969)
development cycle as the computer, a Rolls-
Royce would today cost $100, get a million
miles per gallon, and explode once a year, If the human mind was simple enough to
killing everyone inside. understand, we'd be too simple to understand it.
(RobertX. Cringely, InfoWodd magazine) (Emerson Pugh, American writer on technology)

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