Lección 34 · Etapa 3: Planes, peticiones y comparaciones
Obligación: must / have to / need to
PrincipianteObligation: must / have to / need to
Forma y uso
decir que algo es necesario
1.Forma
Tres maneras de decir que algo es necesario: must, have to, need to, todas + forma base. Must es un verbo modal; have to y need to funcionan como verbos normales.
| must | have to | need to | |
|---|---|---|---|
| Afirmativa | I / she must go. | I have to go. · She has to go. | I need to go. · She needs to go. |
| Negativa | mustn't go (= no lo hagas) | don't / doesn't have to go (= no es necesario) | don't / doesn't need to go (= no es necesario) |
| Pregunta | Must I go? (poco frecuente) | Do I have to go? · Does she have to go? | Do I need to go? |
| Pasado | — (se usa had to) | had to go | needed to go |
Must nunca lleva -s, to ni do: She must go. Have to / need to son lo contrario: She has to go. Does she need to go?
2.Cuándo se usan
1. have to: necesario por normas, por el trabajo o por las circunstancias (un hecho, no la opinión de quien habla)
I have to wear a uniform at work.
Tengo que llevar uniforme en el trabajo.
Linh has to take two buses to get to school.
Linh tiene que tomar dos autobuses para llegar a la escuela.
Do you have to work on Sundays?
¿Tienes que trabajar los domingos?
2. must: quien habla siente personalmente que es necesario: un recordatorio para uno mismo o una recomendación fuerte
It's late. I must go.
Es tarde. Me tengo que ir.
I must call my grandma this weekend.
Tengo que llamar sin falta a mi abuela este fin de semana.
You must try the coconut coffee here — it's amazing!
Tienes que probar el café de coco de aquí, ¡es buenísimo!
3. must: normas escritas, carteles e instrucciones
All visitors must sign in at the front desk.
Todos los visitantes deben registrarse en la recepción.
Passengers must keep their bags with them at all times.
Los pasajeros deben llevar sus bolsos consigo en todo momento.
4. need to: algo es necesario para un fin o por la situación
My phone is almost dead. I need to charge it.
A mi teléfono casi no le queda batería. Necesito cargarlo.
Do we need to book a table, or can we just walk in?
¿Hay que reservar mesa o podemos llegar sin reserva?
5. have got to: igual que have to, muy frecuente en el habla informal
Sorry, I've got to go — my bus is leaving.
Perdón, me tengo que ir, que mi autobús ya sale.
En inglés estadounidense, must para obligación suena bastante fuerte y formal; los estadounidenses suelen decir have to o have got to (gotta). Si dudas, have to casi siempre funciona.
3.Otros tiempos: usa have to
Must tiene una sola forma y solo habla del presente o del futuro. Para el pasado, después de will / might, en present perfect o después de otro verbo, usa have to.
| Tiempo / forma | Ejemplo |
|---|---|
| Pasado | I had to wait an hour for the bus. |
| Futuro | Prices go up next month, so we'll have to pay more. |
| Might have to | We might have to sell the car. |
| Present perfect | I've had to wear glasses since I was ten. |
| Después de otro verbo | I hate having to get up in the dark. |
4.Mustn't es muy distinto de don't have to
| Significado | Ejemplo | |
|---|---|---|
| mustn't | no lo hagas: no está permitido | You mustn't smoke in here. It's a hospital. |
| don't have to / don't need to | no es necesario: puedes hacerlo si quieres | You don't have to bring food. There's plenty. |
You mustn't touch the paintings.
No está permitido tocar los cuadros.
You don't have to take your shoes off. Come in!
No hace falta que te quites los zapatos. ¡Pasa!
El error típico en español: “no debes” = mustn't (está prohibido), mientras que don't have to = “no tienes que / no hace falta” (es opcional). No los confundas. Mira también la lección “Sin obligación: don't have to / needn't”.
5.Errores comunes
You must to turn off your phone in class.You must turn off your phone in class.
Sin to después de must.
She have to finish her homework.She has to finish her homework.
he/she/it → has to.
Last week I must work every evening.Last week I had to work every evening.
Para el pasado, usa had to.
Do you must wear a helmet?Do you have to wear a helmet?
No uses do con must; pregunta Do you have to…?
We will must show our passports.We will have to show our passports.
Futuro: will have to.
She needs wear a uniform.She needs to wear a uniform.
need como verbo normal → need to + verbo.
Ejemplos
- All students must wear a uniform at this school.
- My brother has to work on Saturdays.
- Did you have to pay for the tickets?
- Yesterday I had to stay late at the office to finish a report.
