Conditional tenses are used to speculate about what
could happen, what might have happened, and what we wish would happen. In
English, most sentences using the conditional contain the word if. Many conditional
forms in English are used in sentences that include verbs in one of the past
tenses. This usage is referred to as "the unreal past" because we use
a past tense but we are not actually referring to something that happened in
the past. There are five main ways of constructing conditional sentences in
English. In all cases, these sentences are made up of an if clause and a
main clause. In many negative conditional sentences, there is an equivalent
sentence construction using "unless" instead of "if".
Conditional sentence type
|
Usage
|
If clause verb tense
|
Main clause verb tense
|
Zero
|
General truths
|
Simple present
|
Simple present
|
Type 1
|
A possible condition and its
probable result
|
Simple present
|
Simple future
|
Type 2
|
A hypothetical condition and its
probable result
|
Simple past
|
Present conditional or Present
continuous conditional
|
Type 3
|
An unreal past condition and its
probable result in the past
|
Past perfect
|
Perfect conditional
|
Mixed type
|
An unreal past condition and its
probable result in the present
|
Past perfect
|
Present contditional
|
The
zero conditional
The
zero conditional is used for when the time being referred to is now or
always and the situation is real and possible. The zero conditional
is often used to refer to general truths. The tense in both parts of the
sentence is the simple present. In zero conditional sentences, the word
"if" can usually be replaced by the word "when" without
changing the meaning.
If clause
|
Main clause
|
If + simple present
|
simple present
|
If this thing happens
|
that thing happens.
|
If you heat ice
|
it melts.
|
If it rains
|
the grass gets
wet.
|
Type
1 conditional
The
type 1 conditional is used to refer to the present or future where the situation
is real. The type 1 conditional refers to a possible condition and its
probable result. In these sentences the if clause is in the simple present, and
the main clause is in the simple future.
If clause
|
Main clause
|
If + simple present
|
simple future
|
If this thing happens
|
that thing will happen.
|
If you don't hurry
|
you will miss the train.
|
If it rains today
|
you will get wet.
|
Type
2 conditional
The type 2 conditional is used to
refer to a time that is now or any time, and a situation that is unreal.
These sentences are not based on fact. The type 2 conditional is used to refer
to a hypothetical condition and its probable result. In type 2 conditional
sentences, the if clause uses the simple past, and the main clause uses the
present conditional.
If clause
|
Main clause
|
If + simple past
|
present conditional or present
continuous conditional
|
If this thing happened
|
that thing would happen. (but I'm
not sure this thing will happen) OR that thing would be happening.
|
If you went to bed earlier
|
you would not be so tired.
|
If it rained
|
you would get wet.
|
If I spoke Italian
|
I would be working in Italy.
|
Type
3 conditional
The type 3 conditional is used to
refer to a time that is in the past, and a situation that is contrary
to reality. The facts they are based on are the opposite of what is
expressed. The type 3 conditional is used to refer to an unreal past condition
and its probable past result. In type 3 conditional sentences, the if clause
uses the past perfect, and the main clause uses the perfect conditional.
If clause
|
Main clause
|
If + past perfect
|
perfect conditional or perfect
continuous conditional
|
If this thing had happened
|
that thing would have happened.
(but neither of those things really happened) OR
that thing would have been happening.
|
If you had studied harder
|
you would have passed the exam.
|
If it had rained
|
you would have gotten wet.
|
If I had accepted that promotion
|
I would have been working in
Milan.
|
Reference:
https://www.ego4u.com/en/cram-up/grammar/conditional-sentences
