conditional structure

Conditional structure often used in such situations in which we want to speculate the possibility of events either in the future or in the past.

Different verb tenses are used in the conditional part of the sentences.

Types of conditionals

Type	Result
0 conditional	100% happen
1st conditional	50-90% happen
2nd conditional	1-40% happen
3rd conditional	0% impossible

Conditional sentences have TWO clauses

If ... , it ...
.... if ...

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• ZERO conditional
  when and if can be used interchangeably

If ice cream gets warm, it melts.
Ice cream melts if it gets warm.
When the temperature is zero Celsius, it snows.

[condition] + [result]
[result] + [condition]

using adverbs of frequency to modify the certainty of the result

If it rains, I always ...
When the sun shines in NanHai, the weather is usually hot.
I never ... if the...
When I ..., I often ...

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• FIRST conditional
  The first conditional is used to describe the situation in which we want to predict the possible outcome that is based on some conditions. It often not completely sure as it is 100% will happen in ZERO conditionals.

If the weather is nice, I'll go running.

using won't for negative results

if the project doesn't finish, I won't graduate from college.

using 1st for warnings.

If we don't hurry, we'll miss the train home.
We'll miss our train if we don't hurry.

using other modal verbs instead of will

If the children finish their homework, they can play ...
The children can play ... if they finish...
If you buy a lottery ticket you might win.
You might win if you buy a lottery ticket...
If she ..., it should...
It should... if she ...
if you ... you must...
You must if you ...

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• SECOND conditional
  [If + past tense] , + [would + bare infinitive]
  OR
  [would + bare infinitive] (no comma) + [if + past tense]

If I was rich, I would travel the world.
I would travel the world if I was rich.

When I is the subject, I were will be used in a conditional sentence as opposed to I was which makes it sounds more formal or natural.

If I were you, I would go to the doctor.

Using other modals

If she has time, she would usual form ...
                          She might... not very sure
                          She could... possible
                          She should... suggestion

Using the continuous form in 2nd conditional
[If + past tense] , + [would + be + verb-ing]
OR
[If + past tense] , + [would + be + verb-ing]

I would be living in Beijing, if it wasn't so expensive.

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• THIRD conditional
  [If + past perfect tense] , + [would + present perfect tense]
  OR
  [would + present perfect tense] (no comma) + [If + past perfect tense]

If it had started to rain, the picnic would have been canceled.

Using 3rd conditional to express regrets

If I had studied harder, I would have passed my exam.

abbreviation when using would and had

If I'd known it was your birthday, I'd have bought you a present.
would never appears with if in the condition part of the sentence
had can never be have
If I had known... I would...

Using other modals

If she had left earlier, she would... usual form ...
                          She might... not very sure
                          She could... possible
                          She should... suggestion

Using continuous form in 3rd conditional
[If + past perfect tense] , + [would + have been verb-ing]
OR
[would + have been verb-ing] (no comma) + [If + past perfect tense]

If it had been, I would have been...