Utilizamos los verbos modales para expresar precisamente eso, la “modalidad“, es decir, la actitud del hablante respecto a la acción enunciada. Si dices “She can’t arrive in time“, estás indicando que crees que es imposible (actitud, opinión) que ella llegue a tiempo (acción). Aquí tenéis una tabla que resume los principales modales, aunque faltan needn’t (indica que algo no es necesario, no hace falta) y had better (conveniencia, “sería mejor”); ambos aparecen en vuestro libro y en los enlaces que tenéis más abajo.
| Modal | Usage | Example |
| can | ability | I can do several things at the same time. |
| when something is possible | Miracles can happen. | |
| permission | You can go now. | |
| informal requests | Can you come here for a minute? | |
| could | past form of “can” | She said she could pay for us as well. |
| polite requests | Could you move your bag, please? | |
| possibility | It could be that he missed the train. | |
| may | possibility | It may rain tomorrow. |
| ask for or give permission (formal) | May I speak? | |
| might | past form of “may” | He said he might change his mind. |
| possibility | This might fail. | |
| must | you have to do it | You must obey the law. |
| it’s very logical or very likely to happen | They left so early, they must be home by now. | |
| must not/ mustn’t | you are not allowed to do it | You mustn’t smoke in here. |
| shall | future for “I” and “we” | I shall see him tomorrow. |
| questions and suggestions for “I” and “we” | Let’s continue, shall we? | |
| should | the right thing to do | She should call the police. |
| advice | – What should I do? – You should stop thinking about it. | |
| what is likely or expected to happen | We should be back by midnight. | |
| will | future action or states (not plans) | Prices will go up next summer. |
| promises and intentions | It’s alright, I’ll pick it up. | |
| would | past form of “will” | He told me he would come. |
| imagined situations | What would you do if you were him? | |
| for polite requests, offers and invitations | – Would you please sit down? – Would you like some tea? – We are meeting with Sarah next Saturday, would you like to come along? | |
| to say what you want to do or have | I would like a piece of cake. | |
| ought to | the right thing to do | You ought to apologize. |
Aquí tenéis otro resumen interesante, muy claro, con ejemplos y con colorines (aunque también omite el had better) y aquí, el tutorial más completo que he encontrado en la red, con explicaciones y ejercicios de cada verbo (y que es el que os recomiendo seguir).
Sobre “had better“, aquí tenéis una explicación muy buena en flash (con animación y sonido) y aquí por escrito y con ejercicios.
Quien lo lleve peor, puede empezar por el post de la ESO, hacer sus ejercicios (muy sencillicos) y volver luego aquí.
