CONDITIONALS

1. ZERO CONDITIONAL: CERTAINTY.                                                                                                       the zero conditional is use for things that are always true as long as the condition is met.

IF     CONDITION                RESULT              SITUATION                                                                              present simple             present simple                                                                                                       
IF  you heat water to                it boils                  fact universal
     100 degrees celsius          

         present simple             present simple

IF  i drink coffee                i get a headache          fact personal

In these examples, the result will always occur if the condition is met, so the time is not important.

EXAMPLES:  
-If i am late for work my boss gets angry
-If I leave the house at 8am, I catch the bus at 8.15am 
-If you heat butter, it melts
-If you put water in a cooler, it freezes
-If you drop ice in water, it floats.
-If iron gets wet, it rusts

FIRT CONDITIONAL

We use first conditional to talk about events which are possible. the conditional clause can refer to the present or the future.

CONDITIONAL CLAUSE                                                      MAIN CLAUSE 

If + present simple                                                                 - will + bare infinitive

if itrains, we will stay at home

.the conditional clause can come before or after the main clause, we use a comma at the end of the conditional clause when it comes first:

IF you don't try harder, you will fail.

you will fail if you don't try harder.

.other structures are possible,depending on what you want to say:

CONDITIONAL CLAUSE                                                        MAIN CLAUSE 

If + present simple                                                                  modal verb                                            

If you behave yourself                                                             you can come

If  + presentsimple                                                                - be going to (future)
If you don't work                                                                    you're going to fail 

If + present simple                                                                - imperative 
If you need anything                                                               ask

If + present continuous                                                        - will + bare infinitive
If we're leaving soon                                                             I'll get my coat

If + present perfect                                                               - will + bare infinitive
If  I've finished                                                                       I'll be able to come


If + present perfect                                                              - modal verb
If you're finished                                                                    you can go out