Grammar Lesson

Conditional sentences

The conditional sentences are sometimes confusing for learners of English.

Watch out:
1) Which type of the conditional sentences is used?
2) Where is the if-clause (e.g. at the beginning or at the end of the conditional sentence)?

There are three types of the if-clauses.

Type I
condition possible to fulfill

Type II
condition in theory possible to fulfill

Type III
condition not possible to fulfill (too late)

Examples

Long forms and short/contracted forms

Type I

Affirmative (+)

If I study, I will pass the exam.
If I study, I'll pass the exam.

Negative (-)

If I study, I will not fail the exam.If I do not study, I will fail the exam.
If I study, I won't fail the exam.If I don't study, I'll fail the exam.

Type II

+

If I studied, I would pass the exam.
If I studied, I'd pass the exam.

-

If I studied, I would not fail the exam.If I did not study, I would fail the exam.
If I studied, I wouldn't fail the exam.If I didn't study, I'd fail the exam.



Type III

+

If I had studied, I would have passed the exam.
If I'd studied, I'd have passed the exam.

-

If I had studied, I would not have failed the exam.If I had not studied, I would have failed the exam.

If I'd studied, I wouldn't have failed the exam.If I hadn't studied, I'd have failed the exam.

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