This document outlines the forms and uses of four types of conditional sentences in English: Type 0/universal conditionals use the present tense and are used for true facts or instructions. Type 1 conditionals use "if + present" and "will" to describe likely or probable results. Type 2 conditionals use "if + past" and "would" for unreal or improbable situations. Type 3 conditionals use "if + past perfect" and "would have" to describe impossible past results that cannot be changed. The order of clauses can be reversed and "unless" can be substituted for "if not".

1. CONDITIONAL
SENTENCES

2. TYPE ZERO / UNIVERSAL
 FORM
IF + Present,
Present / Imperative
 USE
 True / scientific facts
 Instructions

3.  EXAMPLES
 If you put paper on a fire, it burns
 If the phone rings, answer it

4. FIRST CONDITIONAL (TYPE 1)
 FORM
IF + Present,
WILL
(Must / can / may)
 USE
 Likely / probable results
 Promises, warnings, threats

5.  EXAMPLES
 If we don’t leave now, we’ll miss the train
 If you pass your exam, I’ll give you a job

6. SECOND CONDITIONAL (TYPE 2)
 FORM
IF + Past simple,
WOULD
(Could / Might)
 USE
 Unreal/Improbable situations
(Conditions won’t be met)
 Advice / suppositions contrary to known facts

7.  EXAMPLES
 If you did more exercise, you’d feel better
 If I were you, I wouldn’t drive so fast
 NOTES
 If I were you (Written / formal language)
 If I were / was you (spoken language)
 If he / she / it were (more usual)
 If he / she / it was (more colloquial)

8. THIRD CONDITIONAL (TYPE 3)
 FORM
IF + Past perfect
(HAD + Past Participle),
WOULD HAVE + Past Participle
(Could / Might)
 USE
 Impossible results, we are talking about
something from the past that can’t be
changed.

9.  EXAMPLES
 If
you had phoned me, I would have
told you about the party.
 Hecould have helped me if I had
spoken to him about my problems.

10.  GENERAL FACTS
 We can exchange the order of the clauses
 If you go, I’ll go
 I’ll go if you go
 Connectors
 UNLESS = IF NOT
‘You won’t pass if you don’t study’
‘You won’t pass unless you study’

11. THE
END