Real Conditional

We use real conditionals to talk about factual ideas, and they can be stated in present or future. Modals can also be used, and the one that we choose to use will depend on the degree of certainty being expressed.

When we talk about conditional sentences, they typically include an IF clause and a RESULT clause. We will see some examples of those as we get into the different uses of conditional sentences.

Real PRESENT conditionals

IF clause = simple present

RESULT clause = simple present

These conditional sentences are used to talk about a habitual action/situation, established fact, or general truth. 

Examples:

If I don't eat lunch, I get hungry. (habitual situation) 

Water freezes if the temperature reaches 32^o. (established fact)

If it snows, we might stay home. [modal of possibility]

Real FUTURE conditionals

IF clause = simple present

RESULT clause = simple future [will + base form]

These conditional sentences are used to talk about a future action/situation, established fact, or general truth.

Examples:

If it snows tomorrow, they will probably cancel the game. (future action)

I will watch a movie tonight if I have time. (future action)

Water will freeze if the temperature reaches 32^o. (established fact)

If there is a storm tomorrow, we can't travel. [modal of possibility]

Unreal Conditionals

Unreal conditionals are used to talk about imaginary situations or things that are contrary to fact. We can use unreal conditionals in present/future and past .

Unreal PRESENT/FUTURE conditionals

IF clause = simple past

RESULT clause = would + base form

When using modals, think about the meaning they have. 

Examples: 

I would not do that if I were you. [meaning = I am not you.]

What would he do if he were here right now? [meaning = he isn't here right now]

If I had enough money, I would buy a computer. [meaning = I don't have enough money; would = desired or predicable result]

I could buy a computer if I had enough money. [could = possible option (be able to)]

NOTE: Were is used for both singular AND plural subjects. However, in informal speech, was is sometimes used even though it is not grammatically correct. 

Unreal PAST conditionals

IF clause = past perfect

RESULT clause = would have + past participle

Could can also be used in the RESULT clause. Think about the difference between would and could in the following sentences.

         If they had studied, they would have passed the test. [meaning = they didn't study, so they didn't pass]

If I hadn't slipped on the stairs, I wouldn't have broken my leg. [meaning = I did slip, so I broke my leg]

I would have bought a computer if I had had enough money. [would = desired result]

I could have bought a computer if I had had enough money. [could = possible result]

NOTE: There are a few options for contractions:

I had = I'd

I would have = I'd have OR I would've