Conditional sentencesWe use conditional sentences to describe how an action or situation affects its result.

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3 Types of Conditionals

Conditional sentences contain an if-clause and a main clause.

If I have enough money,conditional clause

Examples :

I will go to US.    main clause

I will go to U.S.    main clause

if I have enough money.    conditional clause

Conditional clause , main clause.

a. If you help me with the dishes (if + pres) , I will help you with your homework.

(will + inf)

b. If ice is heated, it melts. (Pres. tense).

c. If you see Mr. Tung tonight, tell him I am ill. (imperative).

1. If + Present Tense will +inf / present tense / imperative

We do not normally use will or would in the conditional clause, only in the main clause.

2. If + Past Tense 2. If + Past Tense

3. If + Past Perfect Tense3. If + Past Perfect Tense

would + infinitive would + infinitive

would have + past participle would have + past participle

e.g. If I knew her name, I would tell you.

e.g. If I won the lottery, I would have bought a new house.

Uses of the conditional

First conditional

a. Nature: Open condition, what is said in the condition is possible.

b. Time: This condition refers either to present or to future time.

e.g. If the cinema is full, we will go to a restaurant.

e.g. If it rains tomorrow, we will stay at home and

watch TV.

Second conditional

a.Nature: unreal (impossible) or improbable situations.

b. Time: for present unreal events, we put the verb in the condition clause one step back — into the past:

e.g. If I were you, I would tell my father.

If I became president, I would change the medical care policy. (Said by a schoolboy: improbable)

Compare:If I become president, I will change the medical care policy. (Said by a presidential candidate)

Third conditional a. Nature: unreal

b. Time: for past unreal events — things that didn't happen, but we can imagine — we put the verb in the condition clause a further step back — into the past perfect

e.g. If I had studied hard for the exam, I would have passed

it easily. (But in fact, you did’t study hard.)

For the second conditional, were replaces was

If I were a rich man, I would stop working as a clerk.

If I were to lose my job, I wouldn't be able to pay for my dream car.

Instead of if not, we can use unless.

“ if ” + negative action = “unless” + positive action

The meaning of both sentences is the same, but the actionafter ‘unless’ (close) is the opposite of the action after ‘if’ (don’t close).

Compare:Your bird will fly away if you don’t close the window.

Your bird will fly away unless you close the window.

Let us take a quiz to see how well you understand the grammar form.

Reviewing the online grammar notes at the following URL, under the “ Conditional Verb Form” on the homepage of the Guide to Grammar and Writing. will help you understand the different uses of conditional sentences that, ultimately, will help you to use it.

http://webster.commnet.edu/HP/pages/darling/grammar/conditional.htm