Sabtu, 04 Juli 2015

IF CONDITIONAL



Conditional tenses are used to speculate about what could happen, what might have happened, and what we wish would happen. In English, most sentences using the conditional contain the word if. Many conditional forms in English are used in sentences that include verbs in one of the past tenses. This usage is referred to as "the unreal past" because we use a past tense but we are not actually referring to something that happened in the past. There are five main ways of constructing conditional sentences in English. In all cases, these sentences are made up of an if clause and a main clause. In many negative conditional sentences, there is an equivalent sentence construction using "unless" instead of "if".
Conditional sentence type
Usage
If clause verb tense
Main clause verb tense
Zero
General truths
Simple present
Simple present
Type 1
A possible condition and its probable result
Simple present
Simple future
Type 2
A hypothetical condition and its probable result
Simple past
Present conditional or Present continuous conditional
Type 3
An unreal past condition and its probable result in the past
Past perfect
Perfect conditional
Mixed type
An unreal past condition and its probable result in the present
Past perfect
Present contditional
The zero conditional
The zero conditional is used for when the time being referred to is now or always and the situation is real and possible. The zero conditional is often used to refer to general truths. The tense in both parts of the sentence is the simple present. In zero conditional sentences, the word "if" can usually be replaced by the word "when" without changing the meaning.
If clause
Main clause
If + simple present
simple present
If this thing happens
that thing happens.
If you heat ice
it melts.
If it rains
the grass gets wet.

Type 1 conditional
The type 1 conditional is used to refer to the present or future where the situation is real. The type 1 conditional refers to a possible condition and its probable result. In these sentences the if clause is in the simple present, and the main clause is in the simple future.

If clause
Main clause
If + simple present
simple future
If this thing happens
that thing will happen.
If you don't hurry
you will miss the train.
If it rains today
you will get wet.
Type 2 conditional
The type 2 conditional is used to refer to a time that is now or any time, and a situation that is unreal. These sentences are not based on fact. The type 2 conditional is used to refer to a hypothetical condition and its probable result. In type 2 conditional sentences, the if clause uses the simple past, and the main clause uses the present conditional.
If clause
Main clause
If + simple past
present conditional or present continuous conditional
If this thing happened
that thing would happen. (but I'm not sure this thing will happen) OR
that thing would be happening.
If you went to bed earlier
you would not be so tired.
If it rained
you would get wet.
If I spoke Italian
I would be working in Italy.
Type 3 conditional
The type 3 conditional is used to refer to a time that is in the past, and a situation that is contrary to reality. The facts they are based on are the opposite of what is expressed. The type 3 conditional is used to refer to an unreal past condition and its probable past result. In type 3 conditional sentences, the if clause uses the past perfect, and the main clause uses the perfect conditional.
If clause
Main clause
If + past perfect
perfect conditional or perfect continuous conditional
If this thing had happened
that thing would have happened. (but neither of those things really happened) OR
that thing would have been happening.
If you had studied harder
you would have passed the exam.
If it had rained
you would have gotten wet.
If I had accepted that promotion
I would have been working in Milan.

Mixed type conditional
The mixed type conditional is used to refer to a time that is in the past, and a situation that is ongoing into the present. The facts they are based on are the opposite of what is expressed. The mixed type conditional is used to refer to an unreal past condition and its probable result in the present. In mixed type conditional sentences, the if clause uses the past perfect, and the main clause uses the present conditional.
If clause
Main clause
If + past perfect or simple past
present conditional or perfect conditional
If this thing had happened
that thing would happen. (but this thing didn't happen so that thing isn't happening)
If I had worked harder at school
I would have a better job now.
If we had looked at the map
we wouldn't be lost.
If you weren't afraid of spiders
you would have picked it up and put it outside.

source :  http://www.edufind.com/english-grammar/conditional/