Senin, 17 Maret 2014

conditional sentences



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

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