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.

typecondition
Zerocondition always fulfilled
1stcondition possible to fulfill
2ndcondition in theory possible to fulfill
3rdcondition not possible to fulfill (in the past)

1. Form

typeif-clausemain clause
ZeroPresent SimplePresent Simple
1stPresent Simplewill + infinitive
2ndPast Simplewould + infinitive *
3rdPast Perfectwould + have + past participle *
 

2. Examples (if-clause at the beginning)

typeif clausemain clause
ZeroIf you heat ice,it melts.
1stIf I study,I will pass the test.
2ndIf I studied,I would pass the test.
3rdIf I had studied,I would have passed the test.

3. Examples (if-clause at the end)

typemain clauseif-clause
ZeroIt meltsIf you heat ice.
1stI will pass the testif I study.
2ndI would pass the testif I studied.
3rdI would have passed the testif I had studied.
 

4. Examples (affirmative and negative sentences)

type Examples
  long formsshort/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.