More English Grammar

The English Conditional

There are a number of structures in English that are called the conditionals which are used to talk about possible or imaginary situations. A "Condition" is a "situation or circumstance".

For example: If a certain condition is true, then a particular result happens.

There are four basic conditionals that we use in English.

A) Zero Conditional: Certainty

The Zero conditional is used 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 100 degrees celsius,	it boils.	fact- universal
	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. 

B) First Conditional: A real possibility in the future

A First Conditional sentence is one connecting two future actions, where one must take place before the second is possible. Take a student who wants to go to university but hasn't got the results of their exams yet. They cannot go to university until they have received their results. In the case of a good student who is expected to get good grades, then there is a good possibility of achieving the marks required to get to university, so the following sentence could be used:

IF	Condition	Result
	present simple	WILL + base verb
If	she gets good grades,	she will go to university.

We are talking about the future, but we use a present tense for the condition and will for the result. In this case, the person is sure about going to university. We can use other modal verbs in the result part of the sentence:

IF	Condition	Result	Possibility
If	she gets good grades,	she will go to university.	If the condition is met, then she definitely will go
If	he gets good grades,	he may go to university.	He is not sure about going to university.
If	she gets good grades,	she should go to university.	The speaker is expressing his or her opinion, giving advice.
If	he gets good grades,	he can go to university.	This means that it is possible.
If	she gets good grades,	she could go to university.	This means that it is possible, but not that likely.
If	he gets good grades,	he might go to university.	This means that it is possible, but not that likely.

We can also use different present forms in the condition part of the sentence:

IF	Condition	Reason for tense	Result
	present simple	an action in the future
If	I see her,		I'll ask her about it.
	present progressive	an unfinished present action
If	they are still working,		I'll go home.
	present progressive	a future arrangement
If	they are going,		I'll stay at home.
	present perfect	a finished action related to now
If	you have finished your meal,		I'll clear away the plates.
	WILL + base verb	making an agreement	WILL + base verb
If	you will work late today,		I will let you have Friday off.
	WILL + base verb	expressing displeasure because someone insists on doing something	WILL + base verb
If	you will drive too fast,		the police will stop you.

C) Second Conditional: Imaginary Present or Unlikely Future

The Second Conditional can be used to talk about imaginary present situations, where we are imagining something different from what is really the case. We can also use it to talk about things in the future that are unlikely to happen, as the condition is unlikely to be met. We use the past tense in the condition part and would for the result.

IF	Condition	Time	Result	Possibility
	past simple	present	WOULD + base verb	impossible
If	I had the time,		I would learn Italian.	I don't have the time, so I'm not going to learn Italian.
	past simple	future	WOULD + base verb	unlikely
If	I won the lottery		I would travel around the world.	There's a very small chance of winning the lottery, so the trip is unlikely

We can use other modal verbs in the past tense in the result part of the sentence:

IF	Condition	Result	Certainty
	past simple	WOULD + base verb
If	I had the time,	I would learn Italian.	Although unlikely to happen, the speaker is sure that they would do it given the opportunity.
If	I had more time,	I might learn Spanish.	Although unlikely to happen, it is only a possibility anyway.
If	I had more time,	I should learn some more about IT.	Although unlikely to happen, the speaker is saying that it would be a good idea, but is not committed to it.
If	I had more time	I could learn Hindi.	Although unlikely to happen, it is only a possibility anyway.

With the verb to be, there are two forms that can be used with I, he, she & it:

IF	Condition	Result
I, he, she, it	Were
If	I were you,	I'd marry her.
I, he, she, it	Was
If	I was you,	I'd marry her.

D) Third Conditional: Imaginary Past

The third conditional is used when we are talking about the past and imagining something different from what actually happened:

	Condition	Result	What actually happened
	Past Perfect	WOULD HAVE + Past Participle
If	I had known,	I would have helped.	I didn't know and didn't help.

IF	Condition	Result	Certainty
	past perfect	WOULD HAVE+ past participle
If	I had known,	I would have helped.	Although this didn't happen, the speaker is sure about the result.
If	I had known,	I could have helped.	Although this didn't happen, the result is only a possibility.
If	I had known,	I might have helped.	Although this didn't happen, the result is only a possibility.
If	you had known,	you should have helped.	Although this didn't happen, it is only a good suggestion or piece ofadvice.

There are some more conditionals formed by mixing some of these four. To learn more about these, see our glossary entry: English Conditionals.

 Structure of Conditional Sentences

The structure of the conditionals is straightforward. There are two basic possibilities in terms of order in the sentence:

IF	Condition	Result
If	it rains,	we will get wet

or like this:

Result	IF	Condition
We will get wet	if	it rains.

Notice that we only use a comma in the first example.

Conditionals: Time and Probability Table

Probability	Conditional	Example	Time
Certain	zero conditional	If you heat water to 100 degrees celsius, it boils	any time
Likely	first conditional	If it rains, I will stay in.	future
Unlikely	second conditional	If I won the lottery, I would retire.	future
Impossible	second conditional	If I had the money, I would lend it to you	present
Impossible	third conditional	If I had seen him, I would have given him the message.	past

Read more on: http://www.usingenglish.com/glossary/conditionals.html

Fernando