CONDITIONAL SENTENCES - GRAMMAR

The Zero Conditional: We use the zero conditional when talking about things which are always true, or generally true.

Structure:

If + Simple Present, + Simple Present     OR        Simple Present + If + Simple Present

Note:
We can use "when" instead of "if."

The First Conditional: We use first conditional when talking about possible future events.

Structure:

If + Simple Present,+ Will     OR            Will+ If + Simple Present

Note:
You can use these modal verbs instead of will: can, may.

The Second Conditional: We use the second conditional when talking about future events that are not likely to happen. We also use the second conditional when talking about things which are contrary to the present facts.

Structure:

If + Simple Past, + Would + Base Form   OR     Would + Base Form + If + Simple Past

Note:
You can use these modal verbs instead of would: could, might.

The verb BE

The verb BE has a special rule in this case.

Usually we say: I was, he was, she was, it was, we were, you were, they were.

However, in these cases, we use: I were, he were, she were, it were, we were, you were, they were.

In other words: "were" is the only form.

Examples:

If I were you I would apologize. (In reality I am not you.)

I would fight back,if I were you. (In reality I am not you.)

The Third Conditional: We use the third conditional when talking about things which are contrary to the past facts. In other words: events that did not happen in the past.

Structure:

If + Past Perfect, + Would have + Vpast parti   OR   Would have + Vpast parti + If + Past Perfect

Note 1:
the short form of had is'd.
For example: If he'd passed his exams,he would get a diploma.


Note 2:
You can use these modal verbs instead of would have:
should have, could have, might have.

English Conditionals Summary Table

Conditional	Time Frame	Probability	Example
First Conditional	Future	Possible	If I meet Helen, I will invite her to the party.
Second Conditional	Future	Unlikely	If you studied more, you would pass the exam.
Second Conditional	Present	Unreal/ Imaginary	If I were you, I'd buy the house.
Third Conditional	Past	Impossible	If you had studied hard, you would have passed the exam.
Zero Conditional	Always/Generally	Certain	If you heat ice, it melts.