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Conditional Sentences – A Summary

Conditional sentences

Conditional sentences describe the result of something that might happen (in the present or future) or might have happened, but didn’t (in the past).

They are made using different English verb tenses with an ‘if clause’. The ‘if clause’ can go at the beginning or at the end of the conditional sentence.

There are four main types of conditional sentences.

type condition
Zero condition always fulfilled
1st condition possible to fulfill
2nd condition in theory possible to fulfill
3rd condition not possible to fulfill (in the past)

1. Form

type if-clause main clause
Zero Present Simple Present Simple
1st Present Simple will + infinitive
2nd Past Simple would + infinitive *
3rd Past Perfect would + have + past participle *
 

2. Examples (if-clause at the beginning)

type if clause main clause
Zero If you heat ice, it melts.
1st If I study, I will pass the test.
2nd If I studied, I would pass the test.
3rd If I had studied, I would have passed the test.

3. Examples (if-clause at the end)

type main clause if-clause
Zero It melts If you heat ice.
1st I will pass the test if I study.
2nd I would pass the test if I studied.
3rd I would have passed the test if I had studied.
 

4. Examples (affirmative and negative sentences)

type   Examples
    long forms short/contracted forms
1st + If I study, I will pass the test. If I study, I‘ll pass the test.
If I study, I will not fail the test.
If I do not study, I will fail the test.
If I study, I won’t fail the test.
If I don’t study, I‘ll fail the test.
2nd + If I studied, I would pass the test. If I studied, I‘d pass the test.
If I studied, I would not fail the test.
If I did not study, I would fail the test.
If I studied, I wouldn’t fail the test.
If I didn’t study, I‘d fail the test.
3rd + If I had studied, I would have passed the test. If I‘d studied, I‘d have passed the test.
If I had studied, I would not have failed the test.
If I had not studied, I would have failed the test.
If I‘d studied, I wouldn’t have failed the test.
If I hadn’t studied, I‘d have failed the test.

* We can substitute could or might for would (should, may or must are sometimes possible, too).

  • I would pass the test.
  • I can pass the test.
  • I could pass the test.
  • I might pass the test.
  • I may pass the test.
  • I should pass the test.
  • I must pass the test.