Unit 23: First conditional | Mệnh đề If loài 1

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Meaning and use

We use the first conditional to talk about possible future situations (or ‘conditions’) and their results.We use if for things we think are likely to happen, and when for things we think are certain to happen.

If I visit London, I’ll stay with friends.

It is’t certain that I will go to London.

When I visit London, I’ll stay with friends.

It’s certain that I will go to London.


A conditional sentence usually has two parts: the if/when part and the result (main) part. For the first conditional we use the present simple in the if/when part, and will + infinitive (without ‘to’) in the main part.

Conditional clause (if/when part) + Main clause (main part)
If/When + present simple – will + infinitive without to

The two parts can be in any order. When we write, when the if part comes first, we put a comma between the if/when part and the main part. We don’t use a comma when the main part comes first.

If I visit London, I’ll stay with my friends.
I’ll stay with my friends if I visit London.

When she gets home tonight, she’ll give you a call.
She’ll give you a call when she gets home tonight.


If you’re late, we’ll wait for you.
When I get home, I’ll call you.
They’ll go to the beach if it’s sunny.


When I get home, I won’t watch TV.
If we don’t hurry, we’ll miss the train.
They won’t go to the beach if it isn’t sunny.


When you finish school, what will you do?
How will he feel if he doesn’t get the job?
If you pass your exams, will you go to university?

Short answer Yes, I will. / No, I won’t.

Take Note: modals

We can use modals such as may, might, can or should in first conditional sentences. May and might show we are less certain than when we use will.

We might be late if the shops are busy.
If I feel unwell tomorrow, I may stay at home.
You shouldn’t use the kettle if it isn’t working properly.
If you can’t finish your homework tonight, you can’t go out tomorrow.
When you can smell the cake, you’ll know that it’s cooked.

Take note: going to and present continuous with future meaning

We can use going to or the present continuous with future meaning in the if/when part or the main part.

If we don’t leave right now, we’re going to be late.
If you’re playing tennis later, you’ll need to take your racket.

Take note: as long as and unless

We can use as long as and unless with the same meaning as if and if not:

As long as we leave now, we won’t be late. (= If we leave now, we won’t be late.)
Unless we leave now, we’ll be late.
 (= If we don’t leave now, we’ll be late.)

Spoken English

The will in the first conditional can be shortened to ’ll in both speaking and informal writing. In the negative form, will not can be shortened to won’t.

If I lose my umbrella, I’ll buy another one.
We won’t be pleased if we miss our flight.

It is sometimes difficult to hear the shortened form ’ll before the infinitive. But it’s important to remember it!

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