IF AND THE CONDITIONAL

The 'zero' conditional, where the tense in both parts of the sentence is the simple present:

If + simple present
If you heat ice
If it rains

                   simple present
                   it melts.
                   you get wet.

In these sentences, the time is now or always and the situation is real and possible. They are
often used to refer to general truths.

The Type 1 conditional, where the tense in the ´if´ clause is the simple present, and the tense in
the main clause is the simple future

If + simple present
If it rains
If you don't hurry

                   Simple future
                   you will get wet
                   we will miss the train.

In these sentences, the time is the present or future and the situation is real. They refer to a
possible condition and its probable result.

Study these examples:

I´ll phone you when I get home.

We´ll go out when it stops raining.

The time in the sentence is future, but we use a present tense (I get, it stops) in the when part
of the sentence. We do not use will in the when part.


The same thing happens after while / before / after / as soon as / until or till:

I´m going to read a lot while I´m on holiday.

I´ll go back home on Sunday. Before I go, I´d like to visit the museum.

Wait here until I come back.


You can also use the present perfect (have done) after when / after / until / as soon as:

Can I borrow that book when you´ve finished with it?

Don´t say anything while Ian is here. Wait until he´s gone.

If you use the present perfect, one thing must be complete before the other (so the two things do
not happen together).

When I´ve phoned Kate, we can have dinner.

(= First I´ll phone Kate and after that we can have dinner).


Compare when and if:

We use when for things which are sure to happen:

I´m going shopping later. When I go shopping, I ´ll buy some food.


We use if for things that will possibly happen:

If it´s raining this evening, we won´t go out.

I might go shopping later. (it´s possible) If I go shopping, I´ll buy some food.

The Type 2 conditional, where the tense in the 'if' clause is the simple past, and the tense in the
main clause is the present conditional:

If + simple past
If it rained
If you went to bed earlier

                          Present conditional
                          you would get wet
                          you wouldn't be so tired.

In these sentences, the time is now or any time, and the situation is unreal. They are not based on
fact, and they refer to an unlikely or hypothetical condition and its probable result.

In the other part of the sentence (not the if-part) we use would/ wouldn´t.

Could and might are also possible:

If you took more exercise, you might feel better.

It it stopped raining, we could go out.