Conditionals

1. Zero Conditional
Certainty
We use the so-called zero conditional when the result of the condition is always true, like a scientific fact.
Take some ice. Put it in a saucepan. Heat the saucepan. What happens? The ice melts (it becomes water). You would be surprised if it did not.

IF CONDITIONAL       RESULT


PRESENT SIMPLE   PRESENT SIMPLE
If you heat ice              it melts.
Notice that we are thinking about a result. That is always true for this condition. The result of the condition is an absolute certainty. We are not thinking about the future or the past, or even the present. We are thinking about a simple fact. We use the present simple tense to talk about the conditional. We also use the present simple tense to talk about the result. The important thing about the zero conditional is that the condition always has the same result.
Look at some more examples:

-If you add two and two, you get four
-If you heat water to 100 º, it boils.
-If it rains, I get wet.
-If you travel to Europe, you have to change the hour.
-If I had won the lottery, I would have traveled around the world.


2. First Conditional
Real possibility
We are talking about the future. We are thinking about a particular condition or situation in the future, and the result of this condition. There is a real possibility that this condition will happen. For example, it is morning. You are at home. You plan to play tennis this afternoon. But there are clouds in the sky. Imagine that it rains. What will you do?

IF CONDITION        RESULT


PRESENT               SIMPLE WILL + BASE VERB
If it rains                    I will stay at some.

Notice that we are thinking about a future condition. It is not raining yet. But the sky is cloudy and you think that it could rain. We use the present simple tense to talk about the possible future condition. We use WILL + base verb to talk about the possible future result. The important thing about the first conditional is that there is a real possibility that the condition will happen. Here are some more examples (do you remember the two basic structures: (IF condition result) and (result IF condition)?)
Examples:
-If it rains today, I'll stay at home.
-If he is busy now, I will come back tomorrow.
-If I have time, I'll visit my parents this afternoon.
-If it is warm tomorrow, we'll go to the beach.
-If it is cold, you must wear warm clothes.
-If he doesn't do his homework, he cannot go to the party.
-If she doesn't call you, you can call her.
-If you work hard, you may become a millionaire someday.


3. Second Conditional
Unreal possibility or dream
The second conditional is like the first conditional. We are still thinking about the future. We are thinking about a particular condition in the future, and the result of this condition. But there is not a real possibility that this condition will happen. For example, you do not have a lottery ticket. Is it possible to win? No! No lottery ticket, no win! But maybe you will buy a lottery ticket in the future. So you can think about winning in the future, like a dream. It`s not very real, but it`s still possible.

IF CONDITION        RESULT


PAST SIMPLE       WOULD + base verb
If  I won the lottery   I would buy a car.

Notice that we are thinking about a future condition. We use the past simple tense to talk about the future condition. We use WOULD +base verb to talk about the future result. The important thing about the second conditional is that there is an unreal possibility that the condition will happen.

Here are some more examples:

-If I won the lottery, I would travel around the world.
-If I were in Brazil, I would go to Rio de Janeiro.
-If I were you, I would buy that car.
-If he were in my place, he wouldn't do this.
-If I had more money, I would buy a nice apartment.
-If she had more time, she would travel more often.
-If it were not raining, we could go out.
-If we didn't have to work today, we could have a picnic.



4. Third Conditional
No possibility
The first conditional and second conditionals talk about the future. Whit the third conditional we talk about the past. We talk about a condition in the past did not happen. That is why there is no possibility for this condition. The third conditional is also like a dream, but with no possibility of the dream coming true.
Last week you bought a lottery ticket. But you did not win.

CONDITION                    RESULT


PAST PERFECT           WOULD HAVE + past participle
If I had won the lottery     I would have bought a car.

Notice that we are thinking about an impossible past condition. You did not win the lottery. So the condition was not true, and that particular condition can never be true because it is finished. We use the past perfect tense to talk about the impossible past condition. We use WOULD HAVE + past participle to talk about the impossible past result. The important thing about the third conditional is that both the condition and result are impossible now.
Examples:

-If I had won the lottery, I would have traveled around the world.
-If I had seen him, I would have told him about you.
-If I had known the answer, I would have raised my hand.
-If she had come on Saturday, I would have seen her.
-If they had left earlier, they would have arrived on time.
-If we had studied harder, we might have passed the test.
-If you had gone to Brazil, you would have had lots of fun.
-If I hadn't been so busy, I could have helped you.