Monday, 20 May 2013

MODAL VERBS (THEORY AND EXERCISES)


MODAL VERBS (THEORY AND EXERCISES) 1º y 2º BACHILLERATO


Un verbo modal es aquel que se usa en combinación con un verbo principal para expresar obligación, prohibición, capacidad o habilidad para realizar alguna tarea, para hacer recomendaciones, etc.

Ex. Ralph can speak three languages.
       You know you shouldn´t smoke, so why do you do it?

¡TOMA NOTA!

*    Son verbos incompletos, es decir, les faltan tiempos verbales. No tienen participio ni infinitivo. Al faltarles tiempos, utilizan otros verbos para completar su conjugación. Así, “can” se completa con “be able to” , “must” con “have to”, etc.
*    No llevan  -s en la tercera persona del singular del presente simple, excepto el verbo “have (got)” y “be able to”.
*    Todos van seguidos de un verbo en infinitivo sin “to” , excepto “ought to”, “have to”, “be able to” y “used to”.
*    Como no necesitan verbo auxiliar, construyen la interrogativa invirtiendo el orden del sujeto y el verbo, y la negativa añadiendo “not”.
*    Nunca uses “do, does, o did” en las preguntas en las que ya estén otros verbos modales como “can, must, etc..


1.     OBLIGACIÓN

·        Must (deber, tener que): “you must train very hard if you want to be a successful athlete”.
·        Have to (tener que): “I have to get up at six every morning except Sundays”.


NOTA: “must” se utiliza para dar órdenes, mandatos, obligaciones. Si el que habla desea suavizar esta autoridad, se suele usar “have to”. “Have to y must” se complementan porque tienen un significado similar. Por ello se utiliza “have to” en todos los tiempos que faltan a “must” (por ejemplo, “had to” es el pasado de” must” y “will have to” sería el futuro de “must”).

2.     PROHIBICIÓN

·        Mustn´t (no deber): “ You mustn´t make a noise during the exam”.
·        Aren´t/weren´t allowed to (no estar permitido/no estaba permitido): “Teachers aren´t allowed to smoke inside the school”.
·        Can´t/couldn´t (no poder/ no podíamos): “You can´t take photos using a flash in this museum”.
NOTA: “Mustn´t” es el modal más usual para indicar prohibición.

    3. NECESIDAD

·        Need (necesitar): “We need to buy some butteries for the camera”.

4.     PERMISO (pedir y dar permiso)

·        Can (poder): “I hate that song! Can I put something different on?” “Yes, you can.”
·        May (poder): “May I use your computer ? Yes, you may”.
·        Could (podría): “Could I use your computer?
·        Are/were allowed to (permitir): “My sister is allowed to use a dictionary in her translation exams at university. Incredible!”.

NOTA: “Can, could y may” son los modales más comunes para pedir y dar permiso. “Can y could” se utiliza en un contexto informal y “May” se utiliza en un contexto formal.

5.     AUSENCIA DE OBLIGACIÓN O DE NECESIDAD

·        Needn´t (no necesitar): “You needn´t give me back my camera until I go on holiday next month.”
·        Don´t have to/didn´t have to (no es necesario que ):”Jimmy doesn´t have to retake any exams; he passed them all first time.
NOTA: En este sentido “don´t have to” tiene un sentido más fuerte que “needn´t”.
En este contexto “have to” necesita el auxiliar ”DO” para interrogar y negar (you don´t have to……/do you have to ….?)

6.     RECOMENDACIONES, SUGERENCIAS, CONSEJOS, OPINIONES

·        Should (debería):”Brian should buy a new computer”
·        Ought to (debería): “Bob ought to be more careful when he is driving: he is a real danger to pedestrians.
·        Could (podrías):” You could ask your parents to lend you some money if you haven´t got enough.
NOTA: “Should” es el modal más común para indicar una recomendación. Es prácticamente idéntico a “ought to” , pero este verbo no es tan frecuente como should.

7.     HABILIDAD, CAPACIDAD Y CONOCIMIENTO (PRESENTE)

·        Can (saber):” Marty can play the guitar better than anyone I know”.

NOTA: El verbo que puede sustituir a “can” en este uso es “know how to” (do you know how to cook good Mexican food?)

8. HABILIDAD, CAPACIDAD Y CONOCIMIENTO (PASADO)

·        Could (sabía): “She was a gifted child and could read when she was only three years old.
·        was/were able to (fue capaz de,pudo ): “I was abroad on holiday at the time of the general Election but I was able to vote by post.”
NOTA: Cuando nos referimos a una habilidad que se tuvo en una ocasión concreta del pasado se utiliza “was able to”.

9. AUSENCIA DE HABILIDAD O CAPACIDAD EN EL PRESENTE

·        Can´t (no sabe):”My father can´t drive but my grandmother can.


10. AUSENCIA DE HABILIDAD O CAPACIDAD EN EL PASADO

·        Couldn´t ( no sabía/no podía):”Did you know that Einstein couldn´t speak fluently until he was nine?
·        Wasn´t/weren´t able to “no fue capaz de/no pudo); “Despite playing well, they weren´t able to score the goals they needed to qualify”.


11. POSIBILIDAD/INCERTIDUMBRE

·        Se utiliza “might, may o could” + infinitivo para hablar de posibilidad en el futuro o de posibilidad referida a actividades presentes.
·        May (puede que, tal vez): “Some students may fail the exam”.
·        Might (pudiera ser que): “They might go to the opera, but they prefer rock concerts.
·        Could (podría): “He could be at a friend´s house”.
NOTA: “Could” es menos frecuente que “may y might”
“Might” es una posibilidad más incierta que “May”

·        Se emplea may, might o could + be+ Ving para hablar de actividades que pueden estar ocurriendo en el momento de hablar (Joe might be doing his homework or he could be watching the football on tv.

12. DEDUCCIONES

Una deducción consiste en llegar a una conclusión a través de una interpretación lógica que se apoya en algún tipo de evidencia. Algunas veces la conclusión es muy probable (estamos seguros de ella o casi seguros) y otras veces, más que ser una conclusión probable, se trata de una conclusión posible (no estamos muy seguros de ella).
·        Must +  V infin. (debe ): para referirnos a conclusiones probables expresadas en forma afirmativa de las que estamos seguros o casi seguros. Ex.”Pamela isn´t a t home and I know she works a lot. She must be at work.
·        Can´t + V infinit (no puede): para referirnos a conclusiones probables expresadas en forma negativa de las que estamos seguros o casi seguros. Ex.”Teresa can´t like dancing very much. She hardly ever dances when I see her at the disco.  
·        Must/can´t+ be+ Ving : para expresar conclusiones probables de las que estamos seguros o casi seguros y que se refieren a hechos que están ocurriendo en el momento de hablar.Ex: “Chris is very quiet, isn´t he? Yes, he must be thinking about something.

13. HACER OFRECIMIENTOS

·        Can: “Can I help you” (¿Te puedo ayudar?) INFORMAL
·        Will: “Never mind, I will pick you up tomorrow morning. (No te preocupes, te recogeré mañana por la mañana). FORMAL
·        Would: “Would you like anything from the shop? (¿Querrías algo de la tienda?) FORMAL

14. PEDIR  A OTRA PERSONA QUE HAGA ALGO

·        Can/could. Ex. “Can/could you close the door?” INFORMAL
·        Will/would. Ex. Would/will you close the door, please? FORMAL

15. EXPRESAR HÁBITOS Y RUTINAS EN EL PASADO

·        Would: “When I was a child we´d go to Scotland every summer” ( Cuando era un niño íbamos a Escocia todos los veranos).
·        Used to: “She used to play with me in the playground when we were at school. (Jugaba conmigo en el patio cuando estábamos en el colegio).

16. OFRECERSE UNO MISMO PARA HACER ALGO
·        Shall: “shall I carry your bags?(¿Te llevo las bolsas?) FORMAL
·        Can: “Can I carry your bags? (¿Puedo llevarte las bolsas?) INFORMAL
NOTA: “Shall” se utiliza sólo con la primera persona (I/we).


MODALES PERFECTOS

Se forman añadiendo al modal un infinitivo perfecto, cuya estructura es “have + Vparticipio -ed, si es regular o la tercera columna de los verbos irregulares. Se usan para referirnos a acciones pasadas.

·        Needn´t  + have +Vparticipio (no necesitaba haber/ no tenía que haber…): para señalar que una persona hizo algo aunque esto no hubiera sido necesario.Ex: “She needn´t have taken a taxi. I would have picked her up if she had phoned me.
·        Should/ought to + have + Vparticipio (debería haber …): para indicar que una acción fue poco sensata o que no se siguió un consejo en el pasado.Ex: “He should have locked the door.
·        May/might/could + have + V participio (puede/podría haber …): para hablar a cerca de hechos que posiblemente ocurrieron en el pasado, pero no tenemos certeza absoluta. Si usamos “might”, la suposición es incluso más remota. Ex: She may have made a mistake
·        Must + have + Vparticipio (debe haber…): Para expresar una conclusión probable expresada en forma afirmativa y que se refiere a un hecho del pasado.Ex: Ferry said he woul phone me but he didn´t. He must have forgotten.
·        Can´t + have +  Vparticipio (no puede haber…): Para expresar una conclusión probable expresada en forma negativa de la que estamos seguros o casi seguros y que se refiere a un hecho del pasado.EX: I saw Carolina in the street today. She can´t have gone on holiday yet.      


































1. CIRCLE THE CORRECT ANSWER.

  1. You (may/must) eat three nutritious meals a day if you want to be healthy.
  2. We in France this summer. (Would/ could) we spend a few days with you?
  3. You (shouldn´t/should) be respectful of the elderly.
  4. If you want to have dinner at the restaurant, you (are ableto/ ought to) book a table in advance.
  5. In order to be accepted to university, you (might/have to) have good marks in your exams.

2. FILL IN THE CORRECT FORM OF THE MODALS FROM THE LIST BELOW. THERE MAY BE MORE THAN ONE CORRECT ANSWER.

Should/ought to/ must/ can/ might/ musn´t/ may

The computer is a wonderful invention, however you __________ use it carefully. In order to avoid losing documents, you __________ always save everthing you type. In addition, you ___________ print out a copy of all important documents. One of the greatest fears of computer users is a virus. There are certain dates on which you ________ turn on your computer for fear of infection. Your computer ________ get a virus if you insert used diskettes, so you __________ try to avoid doing so. Moreover, you _______ want to buy an anti-virus program.


3. CHOOSE THE MOST APPROPIATE SENTENCE.

1. We could have bought the house for less money.
a. We really should.                                   B. It is a pitty we didn´t

2. I advised him to spend more time on his studies. Now he is sorry he didn´t listen.
a. He should study more.                                 B. He should have studied more.

3. David would have booked you a ticket.
a. Why didn´t you ask him to?                       B. Why don´t you ask him to?

4. I am an only child. I am sorry my parents had no more children.
a. My parents should have had more children.       B. My parents must have had more children

5. He didn´t come to our meeting yesterday.
a. He must have had another meeting    b. He must have another meeting

4. TRANSLATE THESE SENTENCES INTO ENGLISH

  1. Podriamos haber ido a ver una pelicula.

  1. Deben terminar antes de las 6.

  1. ¿Qué piensas que deberia haber hecho?


5. REWRITE EACH SENTENCE USING A MODAL O MODAL PERFECT.

1.Drinking alcohol while you drive is prohibited by law.
You...
2. Perhaps i will go to the cinema.
I...
3.I am not able to get up early in the morning.
I...
4.I suggest you sleep at least seven hours the night before a big exam
You...
5.It is a pitty we didn´t spend our last holiday in the country.
We...
6.I don´t think I told you all the news.
I...
7.It was wrong of the manager to employ 13 year old children
The manager...
8.He is late for work again. He probably woke up late.
He...


6. ERROR CORRECTION

1.You must to save all the documents on your computer.

2. My father might had helped you yesterday if you had asked.

3. Victor should spent more time studying for yesterday´s exam

4.Young people today ought be more polite to their parents.

5.Noemi can have completed the assignment on time if she had tried.


7.     CHOOSE THE CORRECT WORDS.

  1. This is top secret. You (mustn´t/don´t have to) tell anybody.
  2. Look at those clouds. I think it (must/might) rain soon.
  3. Do you have toothache? Don´t you think you (should/have to) go to the dentist?
  4. I would like to talk to you . (May/Would) I call you at home?
  5. When she was younger, she (can/could) run much faster.
  6. It was very difficult, but Danny (might/ was able to) get a ticket for the football match

8.     CHOOSE THE MOST APPROPIATE SENTENCE TO FOLLOW EACH EXAMPLE

  1. We could have gone to see a film.
  1. What a pity we didn´t go                         b. Why don´t we go?

  1. I should have studied for the exam
a. I knew all the answers                               b. I didn´t know any of the answers

  1. They have been looking forward to the party all week, but they aren´t here yet.
a. They couldn´t have forgotten about it            b. They couldn´t forget about it

  1. He still hasn´t arrived
a. He must take the wrong turning              b. He must have taken the wrong turning

  1. You could have helped her when she asked you to.
  1. Why don´t you?                                      b.. Why didn´t you?

  1. Believe me, I would have visited her
a. I just didn´t have the time                           b. I just won´t have the time


9.     COMPLETE THE SENTENCES USING MODAL PERFECTS.

  1. My motorbike has disappeared.
Someone _______________________________________________________

  1. It is possible she told you a lie.
She ____________________________________________________________
  1. Perhaps he called me, but I was out earlier  He______________________________________________________________

  1. It was wrong of you not to apologise to her.
You ________________________________________________________________



  1. CHOOSE THE CORRECT OPTION.

  1. When David was three years old he  __________ write his own name.
1. must                      2. could                     3. is able to
B. In my opinion, Sheila ___________ apologise for her rude behaviour.
1. should                   2. have to                    3. can
C: Pupils ____________ smoke in the school grounds. It is forbidden.
1. couldn´t                 2. needn´t                    3. musn´t
D. The bus _________ be late because of the heavy rain.
1. should                    2. might                       3. can
E. I´m sorry, I ____________ help you. I don´t know anything about cars.
1. shouldn´t                2. can´t                       3. needn´t             


11. CHOOSE THE CORRECT WORDS:

  1. Look at these clouds. I think it (must/might) rain soon.
  2. Do you have toothache?Don´t you think you (should/have to) go to the dentist?
  3. I would like to talk to you. (May/Would) I call you at home?
  4. When she was younger, she (can/could) run much faster.
  5. It was very difficult , but Danny (might/was able to) get a ticket for the football match.

12. WHAT DO YOU USE TO EXPRESS:

  1. ability in the present and in the past.


  1. Obligation
  2. A request
  3. Possibility in the future
  4. Prohibition                                                                        
  5. Advice.

13. CHOOSE THE CORRECT MODAL VERB.

  1. My brother could walk/might walk before he started talking.
  2. You have worked very hard. You could be /must be tired.
  3. Helen musn´t do/couldn´t do her homework, because she was ill.
  4. The weather forecast says it may rain/should rain tomorrow.
  5. I´ll try to finish, but I can´t have/ might not have  enough time.
  6. Jim always goes on holiday to the same place. He might like/must like it there.

14. TRANSLATE THESE SENTENCES INTO SPANISH.

  1. ¿Podría utilizar tu ordenador?( A un amigo)_________________________________________

  1. ¿Puede usted abrir la ventana? (A una persona mayor)


  1. Puede que vayamos al campo el próximo fin de semana. Incluso podríamos ir al extranjero.


  1. Mis amigos deben vivir ya en su nueva casa pero puede que no hayan llevado los muebles todavía.
________________________________________________________________

  1. No debes comer chicle en clase. Está prohibido.


  1. ¿Vamos al cine esta tarde?


  1. ¿Haría usted el favor de cerrar la puerta?


  1. ¿Podemos irnos hoy antes? (al jefe)_____________________________________________________________

  1. ¿Puedes ayudarme, papá?___________________________________________

  1. ¿Podría usted traer los ejercicios, Mr Smith?____________________________

  1. ¿Leo yo el texto? _________________________________________________

  1. Tendría que tomar más verduras usted. (a un paciente).________________________________________________________

  1. No puedes hablar alto en clase. (A un estudiante)_______________________________________________________

  1. Puede que vivan cerca. _____________________________________________

  1. Podría ser que vinieran. _____________________________________________

  1. ¿Puedes darme un par de euros? (A un amigo)___________________________

  1. ¿le abro la puerta? ________________________________________________

    1. HOW DO YOU SAY:

  1. Mandar u obligar a hacer algo.________________________________________
  2. Ofrecerse a hacer algo. _____________________________________________
  3. Pedir permiso.___________________________________________________
  4. Dar consejo.___________________________________________________
  5. Pedir a otra persona que haga algo.________________________________
  6. Ofrecerse uno mismo a hacer algo._______________________________
  7. Para prohibir algo.___________________________________________
  8. Posibilidad de que algo ocurra.__________________________________
  9. Imposibilidad con respecto al presente.__________________________
  10. Certeza respecto al presente. __________________________________



16. CHOOSE THE CORRECT OPTION.

Students in modern secondary schools in the UK.

Sometimes feel that they have to/should to complain about homework, but life isn´t too bad. It is true that they can´t/must study a lot, but 50 years ago schools were stricter. Students mustn´t/weren´t allowed to speak without permission and had to/needn´t  show teachers a lot of respect. Teachers and head teachers are able to/could use corporal punishment if students broke the rules. Also, in many boarding schools and private schools, senior students (older) need to/were allowed to hit junior students (younger). Juniors had to/must obey the seniors. The seniors could/must tell the juniors to clean their shoes or make their beds. This might/can´t seem strange to teenagers today, but school authorities thought that juniors should/ought to learn how to serve. Fortunately, young people nowadays needn´t/mustn´t worry about that.

17. CHOOSE THE BEST ANSWER:

1.A policeman stopped Mr West for driving through a red light.
He told Mr West that he may have/must have /ought to have stopped at the light.

11. A man is waiting for the results of a driving test.
He thinks he may have/ought to have/shouldn´t have failed.

12. Sally feels ill.
She shouldn´t have/could have/might have eaten so much at the party.

13. My friend didn´t meet me at the restaurant
He must have/might have/could have called to tell me that he wasn´t coming.

14. The Browns are stepping into a new car.
They may have/must have/should have bought a new car.

18. FILL IN THE POSITIVE OR NEGATIVE FORM OF “SHOULD HAVE, MUST HAVE OR COULD HAVE” TOGETHER WITH THE VERB IN BRACKETS

Jim Kelly loves camping.He remembers an early camping experience. “We packed up to leave at 5.00. We _________________(stay) longer because it was so cold. We picked up all the litter carefully, but we  ______________(pay) more attention to our fire. We ______________(leave) the forest without checking that the fire was out. We ______________(notice) that the fire was still burning.
One of the campers looked back and saw leaves burning near the campfire. The wind __________________(blow) the leaves onto the fire. We rushed back and threw water onto the flames. We were lucky that we saw the burning leaves. It __________________(easily cause) a disaster.”

19. CHOOSE THE BEST ANSWER:

1.     It was wrong of Dan not to warn us about the danger.
Dan could have/must have warned us.
2.     There was absolutely no reason for them to come late.
They shouldn´t have/should have come on time.

3.     I´m sure that I told you what happened.
I might have/must have told you what happened.

4.     It´s possible that she left her sweater on the bus.
She must have/may have left her sweater on the bus.

5.     Someone may have told him the bad news.
He ought to have/might have heard the bad news.

6.     They didn´t write although they had our new address.
They could have/might have written.     

20. TRANSLATE THESE SENTENCES INTO SPANISH.

1.     Yo no puedo leer esta carta porque he perdido mis gafas graduadas.

2.     Después de tomar un pequeño descanso, nosotros fuimos capaces de continuar.

3.     Cuando era un niño, él podía bailar como un profesional.

4.     Nosotros podremos viajar a Madrid mañana. El coche está funcionado ahora.

5.     Todos los niños menores de 16 años deben ir al colegio.

6.     Los conductores deben tener una licencia para conducir antes de que ellos conduzcan solos.

7.     Aunque hace sol, puede que mañana llueva. Coge el paraguas y el chubasquero si mañana vas de viaje.

8.     María puede visitarnos la semana próxima, pero no estoy muy seguro.

9.     Nosotros no necesitamos acabar los deberes hoy. Son para el próximo jueves.

10. Nosotros tuvimos que caminar a casa porque perdimos el último autobús anoche.

11. Yo tengo que acostarme temprano durante la semana, pero yo no tengo que acostarme temprano los viernes por la noche.

21. REWRITE THESE SENTENCES REPLACING THE UNDERLINED WORDS.

Can/can´t/could/couldn´t/must/needn´t

1.     I am not able to get up very early in the morning.

2.     You don´t have to shout- I am not deaf.

3.     I have to get a new passport before the summer.

4.     When he was younger, he was able to run much faster.

5.     She is able to help you with your project.

6.     She doesn´t have to return the book today.

7.     Drivers have to observe the speed limit.

8.     Their parents weren´t able to pay for extra lessons.



22. CHOOSE THE CORRECT ANSWER.

1.     Ron doesn´t feel well. He ___________ see a doctor.
a. should                         b. had to                c. ought to

2.     When the children were young, they ________ speak English. Unfortunately, they don´t remember any of it.
a. must                             b. could                  c. might

3.     It ________ rain tomorrow. Take umbrellas and raincoats with you on your trip.
a. can´t                              b. may                    c. must

4.     I ______ speak four languages. My parents taught me all four.
a. can                                 b. need                   c. should

5.     Although I broke my finger, I __________sign my name.
a. was able to                     b. have to                c. couldn´t

6.     You ________ review the work done in class or you will forget it.
a. should                              b. may                   c. needn´t

7.     you __________eat so quickly. You will get a stomach-ache.
a. can´t                                  b. doesn´t have to      c. shouldn´t

8.     As a child, he _________ dance like a professional.
a. can                                    b. could                    c. is able to

9.     They  _________ travel to London tomorrow.
a. can´t                                b. will be able to        c. couldn´t

10. Yesterday, I _________ enter the computer room because I had a special key.
a. was able to                      b. could                      c. can

23. THESE ARE THE SCHOOL RULES. REWRITE THEM USING “MUSTN´T, DON´T HAVE TO, MUST, NEEDN´T, SHOULDN´T”.

1.     Pupils are not allowed to leave the school before classes are over.

2.     Pupils are not allowed to stay in the classroom during breaks.

3.     Pupils are obliged to wear the school uniform every day.

4.     Pupils are not obliged to wear closed shoes. They may wear sandals instead.

5.     Pupils are obliged to participate in gym classes.

6.     Pupils are not obliged to participate in competitive sports games.

7.     Pupils are advised not to leave expensive things in the classrooms.

24. COMPLETE THESE SENTENCES USING “ TO BE ABLE TO, SHOULD, OUGHT TO, MUST, HAVE TO, NEED”

1.     You have burnt yourself. You ________be more careful.
2.     We ______________ leave soon. The last bus leaves in 10 minutes.
3.     I _________________ see you tomorrow. I will have some free time then.
4.     You _______________ rush. There is plenty of time. The film only starts in two hours.
5.     You _______________ be quiet in the library. It is forbidden to make a noise..
6.     We ___________ walk home because we missed the last bus last night.
7.     The police ______________ catch the thief as he was climbing out of a window.
8.     Parents ____________keep medicines way from children. Cleaning fluids are also dangerous.
9.     Paul _____________ drive the car because his mother has broken her hand.
10.  You ___________ worry. I will take care of the children.
11. You ____________ see a dentist regularly. Then, you will have healthy teeth.

25. FILL IN THE BLANKS WITH MUST, MUSTN´T, HAD TO, NEEDN´T.

1.     You _________ throw things out of the car window.
2.     You _________ hurry; we have got plenty of time
3.     The doctor says she _________ stop smoking
4.     He forgot his hat, so he _________ run back home to get it.
5.     You ___________go shopping right now; You can go later.
6.     The matter is very important; you ____________allow me to see the manager right away.
7.     She _________ do her homework last night because she didn´t have time during the day.
8.     After her illness last year, she __________ be very careful not to catch a cold.
9.     Everyone _______ carry some form of identification with them.

26. REWRITE THE FOLLOWING SENTENCES WITH  THE APPROPIATE MODAL.

1.     Perhaps it will rain today. (may)It____________________________
2.     It´s a good idea to take some money with you. (should). You__________________________________________________
3.     Ii´s not necessary to clean your room right now. (need)
You ______________________________________________________

4.     I suggest you say goodbye before you leave. (should)
You ______________________________________________
5.     You know how to do that by yourself. (can)
You _____________________________________________
6.     Parents have an obligation to teach their children the difference between right and wrong.(must)
Parents _____________________________________________
7.     It is necessary for Dad to get up very early tomorrow morning.(have to ).
Dad_____________________________________________________
8.     In the future, children will know how to use computers before the age of five. (to be able to)
In the future children _______________________________________
9.     It is forbidden for boys to ride skateboards in the street. (must).
The boys __________________________________________________
10. It is not necessary to be rich in order to be happy. (have to)
You _______________________________________________________