This document discusses the different types of conditional sentences in English. There are four main types: zero conditional, first conditional, second conditional, and third conditional. Each type uses a different verb tense combination and serves a different grammatical function. The zero conditional refers to general truths using present tense. The first conditional refers to possible future events using present and future tenses. The second conditional refers to unlikely present or future situations using past tense. The third conditional refers to imagined past events using past perfect tense. Mixed conditionals combine tenses to discuss past situations with present results or vice versa.

1. Can – Can´t - Cannot
Could - Couldn´t
May – May not
Might – Mightn´t
Will – Won´t
Shall – Shall not
Would - Wouldn´t
Must – Mustn´t
Should – Shouldn´t
Ought to – Ought not to

2. Son cuatro las principales características de los modal verbs:
1. No tienen infinitivo (por ejemplo, no existe to can)
2. No tienen gerundio (por ejemplo, no existe mighting)
3. No tienen participio (por ejemplo, no existe willed)
4. No llevan ‘s, es, ies’ (por ejemplo, no existe cans)
5. No se usan auxiliares ( por ejemplo, no existe do may / did may)
6. Se usan con otros verbos para modificarlos

3. Can
Expresa habilidad o posibilidad
 I can speak English, but I can´t speak French.
Could
Es el pasado de “can”, pero también se usa para expresar posibilidad.
Además sirve para preguntar con un tono de formalidad (particularmente
hacer solicitudes a quien nos escucha de una manera más respetuosa).
 My dad could run faster when he was younger.
 Could you lend me your computer, please?
 Could you open the door, please?

4. May
Este modal verb se utiliza para expresar posibilidad y probabilidad en el
futuro.
 It is cloudy. It may rain.
También se utiliza para pedir permiso.
 May I go to the bathroom? Yes, you may // No, you may not
Might
Might es usado para dar sugerencias y posibilidades (menos probable que
MAY) y también se usa para peticiones y ofrecimientos.
 It mightn´t rain, even if it´s cloudy, because It´s spring. (doy apoyo)
 My sister might come home for my birthday. (tal vez)

5. Will
Es más conocido por expresar el futuro en inglés, pero también se usa para
expresar una decisión hecha en el momento en que se habla o la intención
de hacer algo.
 I won’t go with you because I have a lot of work
Shall (BRITISH ENGLISH)
Se utiliza de la misma manera que WILL pero en inglés británico más formal
y educado. No se usa en USA.
 If you want to do it, you shall do it!
Should
Este verbo que se traduce al español como “deber” tiene la idea de una
obligación o recomendación.

6. Should
Recomendación, consejo, sugerencias.
 If you feel sick, you should go to the doctor.
 You shouldn´t speak fast English if you don’t feel comfortable.
Ought to
Sinónimo de SHOULD pero mucho más formal y educado.
 If you feel sick, you ought to go to the doctor.
 You ought not to spend your money in videogames.

7. Must
Obligación, una orden que tienes que cumplir. Prohibición cuando es
negativo.
 Students mustn,t speak during the class.
 You must listen while I am speaking.
Would
Se usa para realizar peticiones con amabilidad y también sirve para señalar
acciones constantes en el pasado.
 Would you help me, please?
 I would like a cup of tea, please.
 If I had time, I would go to the concert.

8. Must + have + participio
We use it to make a deduction about something that has happened.
We feel quite sure about it.
1. She must be in the garden. (PRESENT)
2. She must have been in the garden when I called her.
3. If you can´t find your car keys you must have left them
at home.
Can’t + have + participio
We are making a deduction about something that didn´t happen in
the past based on present evidence.
1. He´s just left. He can´t be too far. (PRESENT)
2. He can´t have fallen in love with her. She’s married.
3. You can´t have seen her. She´s at home.

9. May + have + participio
Past unreal possibility. We use it to say that something was possible
in the past but we are not sure.
1. He may take the next train. (PRESENT)
2. He may have taken a different train. I’ll call him.
3. We may have passed the exam, but it was in English.
Might + have + participio
Past unreal small probability. We use it to say that something was
possible in the past, but we know that it didn´t in fact happen.
1. If you really needed the money, you might have sold
the car.
2. If Mary hadn´t been there, my son might have broken
his arm.
MAY
50%
MIGHT
30%

10. Should + have + participio
Past unreal recommendation. We use it to express the idea that
something was desirable or needed but it didn´t take place.
1. She should be at work now. (PRESENT)
2. You should have listened to the teacher.
3. I should have called you yesterday but I forgot.
Shouldn´t + have + participio
We use it to talk about that something that took place but it wasn´t
desirable.
1. She shouldn´t have drank so much. Now you feel
terrible.

11. Needn´t + have + participio
Didn’t need to
It´s the opposite meaning to “SHOULD HAVE”. Both these forms are used to talk
about past events, but there is sometimes a difference in use. When we say
that someone needn't have done something, it means that they did it, but it
was not necessary:
1. You needn´t study hard for the exam. It will easy. (PRESENT)
2. You needn´t have bought more milk. We have got too much.
3. You needn't have washed the dishes. I would've put them in the
dishwasher.
4. I needn't have prepared all that food. They phoned to say they
wouldn't be coming.

12. But we also use didn't need to say that something was not necessary
under circumstances where it was not done:
1. The sun came out so we didn't need to take any rainwear on the trip.
2. We had plenty of petrol in the tank so I didn't need to fill up.
3. We didn't need to wait for long time for them. They arrived just after
us.
Would + have + participio
Past unreal action.
1. If I had guessed the future, I would have taken some precautions
against my pregnancy.

13. We use conditional sentences to say one thing depends on another.
They can be used to talk about real or imaginary situations.
One of the clauses starts with “ if ” (this is the conditional clause).
The other clause talks about the result of the conditional clause
happening.
You can use IF / WHEN / AS LONG AS / UNLESS
The order of the clauses does not change the meaning.
1. If you study hard, you will pass your exam.
2. You will pass your exams if you study hard.
Conditional sentences are often divided into different types:

14. ZERO CONDITIONAL
We use the zero conditional to talk about things that are generally true,
especially for laws and rules.
The structure is:
if + subject + present simple , subject + present simple.
1. If I drink too much coffee, I can't sleep at night.
2. When the sun goes down, it gets dark.
3. You can borrow my surfboard as long as you get it back to me by five
o’clock.

15. FIRST CONDITIONAL
We use the first conditional when we talk about future situations we believe
are real or possible.
The structure is usually:
if + subject + present simple, subject + will + infinitive.
It is also common to use this structure with unless, as long
as, as soon as instead of if.
1. If it doesn't rain tomorrow, we'll go to the beach.
2. River Plate will be top of the league if they win.
3. I'll leave as soon as the babysitter arrives.
4. I won´t stay in London unless I get a well-paid job.

16. SECOND CONDITIONAL
The second conditional is used to imagine present or future situations that
are impossible or unlikely in reality.
The structure is usually:
if + subject + past simple , subject + would (modal) + infinitive
1. If we had a garden, we could have a cat.
2. If I won a lot of money, I would buy a big house in Spain.
3. I wouldn't worry if I were you.
When if is followed by the verb be, it is grammatically correct to say
If I were, if he were, if she were and if it were. But you can use WAS
A. If I were you, I wouldn't mention it.
B. If she was prime minister, she would invest more money in schools.
C. He would travel more if he was younger.

17. THIRD CONDITIONAL
It is used to imagine a different past. We imagine a change in a past
situation and the different result of that change.
The structure is usually:
If + subject + past perfect, subject + would have + past participle.
1. If I had understood the instructions properly, I would have passed the
exam.
2. We wouldn't have got lost if my phone hadn't run out of battery.
3. I definitely would’ve remembered if you’d told me!
4. He wouldn’t have missed the bus if he hadn’t overslept.
5. If they’d told me, I might have been able to help.

18. MIXED CONDITIONALS
We can use mixed conditionals when we imagine a past change with a result
in the present or a present change with a result in the past.
1. Past/Present - the structure is:
If + subject + past perfect, subject + would + infinitive.
Here's a sentence imagining how a change in a past situation would have a
result in the present.
A. If I hadn't got the job in Tokyo, I wouldn't be with my current partner.
B. If I had bought that mobile phone, I wouldn´t have money.

19. 1° CONDITIONAL
IF + PRESENT SIMPLE , + WILL
1. If you don't hurry, you will miss the bus.
ZERO CONDITIONAL
IF + PRESENT SIMPLE , + PRESENT SIMPLE
1. If public transport is efficient, people stop using their cars.
2° CONDITIONAL
IF + PAST SIMPLE , + WOULD + INFINITIVE
1. If I were you, I would accept that job opportunity.

20. MIXED CONDITIONAL
IF + PAST PERFECT, + WOULD + INFINITIVE
1. If we had looked at the map we wouldn't be lost.
3° CONDITIONAL
IF + PAST PERFECT, + WOULD HAVE + PARTICIPLE
1. If only I had worked harder at school, I could have been a doctor.