Conditional sentences in English

Conditional sentences (if-clauses, main clauses)

 

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)?

type	condition
I	condition possible to fulfill
II	condition in theory possible to fulfill
III	condition not possible to fulfill (too late)

Form

type	if clause	main clause
I	Simple Present	will-future (or Modal + infinitive)
II	Simple Past	would + infinitive *
III	Past Perfect	would + have + past participle *

Examples (if-clause at the beginning)

type	if clause	main clause
I	If I study,	I will pass the exam.
II	If I studied,	I would pass the exam.
III	If I had studied,	I would have passed the exam.

Examples (if-clause at the end)

type	main clause	if-clause
I	I will pass the exam	if I study.
II	I would pass the exam	if I studied.
III	I would have passed the exam	if I had studied.

Examples (affirmative and negative sentences)

type		Examples
		long forms	short/contracted forms
I	+	If I study, I will pass the exam.	If I study, I'll pass the exam.
	-	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.
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.
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).

I would pass the exam.

I could pass the exam.

I might pass the exam.

I may pass the exam.

I should pass the exam.

I must pass the exam.

 

Conditional sentences - Special types and structures

Conditional sentences (if-clauses, main clauses)

 

Structure

If-clauses can be clause-initial (1), clause-medial (2) as well as clause-final (3).

(1)	If you like, we can catch a movie.
(2)	We, if you like, can catch a movie.
(3)	We can catch a movie if you like.

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Types

Aside from the typical type I, II, III strucure, conditionals can be divided into two categories:
real and unreal conditionals.

Real Condition

If I have money, I spend it.	Present Real Conditional - type I
If I had money, I spent it.	Past Real Conditional - type I
If I have money, I will/am going to spend it.	Future Real Conditional - type I

Unreal Condition

If I had had money, I would have spent it.		Past unreal Conditional - type III
If I had money, I would spend it.	I think about spending the money TODAY.	Present unreal Conditional - type II
If I had money, I would spend it.	I think about spending the money NEXT WEEK.	Future unreal Conditional - type II

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Special Features

Main clauses with real conditional tenses can have modal verbs.

If I have money, I can spend it.

You can use could and might instead of would in unreal conditional clauses.

If I had money, I could spend it. (I would be able to spend it.)
If I had money, I might spend it. (I would possibly spend it.)

 

Mixed Conditionals

Conditional sentences (if-clauses, main clauses)

Mixed Conditionals

Unreal conditionals (type II + III) sometimes can be mixed, that is, the time of the if clause is different from the one of the main clause.

Past --> Present
If I had taken an aspirin, I wouldn't have a headache now.

Past --> Future
If I had known that you are going to come by tomorrow, I would be in then.

Present --> Past
If she had enough money, she could have done this trip to Hawaii.

Present --> Future
If I were you, I would be spending my vacation in Seattle.

Future --> Past
If I weren't flying to Detroit, I would have planned a trip to Vancouver.

Future --> Present
If I were taking this exam next week, I would be high-strung.