Conditional sentences
Conditional sentences are sentences expressing factual implications, or hypothetical
situations and their consequences. They are so called because the
validity of the main clause of the sentence is conditional
on the existence of certain circumstances, which may be expressed in a dependent
clause or may be understood from the context.
A full conditional sentence (one which expresses
the condition as well as its consequences) therefore contains two clauses: the
dependent clause expressing the condition, called the protasis; and
the main clause expressing the consequence, called the apodosis.[1]
An example of such a sentence (in English)
is the following:
If it
rains the picnic will be cancelled.
Here the condition is expressed by the clause
"If it rains", this being the protasis, while the consequence is
expressed by "the picnic will be cancelled", this being the apodosis.
(The protasis may either precede or follow the apodosis; it is equally possible
to say "The picnic will be cancelled if it rains".) In terms of logic, the protasis
corresponds to the antecedent, and the apodosis to the consequent.
Languages use a variety of grammatical forms and
constructions in conditional sentences. The forms of verbs used in the protasis
and apodosis are often subject to particular rules as regards their tense
and mood. Many languages have a specialized type of
verb form called the conditional mood – broadly equivalent in
meaning to the English "would (do something)" – for use in some types
of conditional sentence.
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
|
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.
sumber :
* http://en.wikipedia.org/wiki/Conditional_sentence
*http://www.englisch-hilfen.de/en/grammar/if.htm
|
