Os verbos auxiliares são verbos que geralmente se usam ao lado do verbo principal e têm a função de acrescentar algo ao significado da oração. Se podem usar também para conjugar verbos em tempos compostos, para fazer e responder perguntas tipo sim/não ou formar frases negativas e a voz passiva.
Os três verbos auxiliares mais comuns, “be”, “have” e “do”, se chamam verbos auxiliares primários.
Assim como os verbos normais, têm o infinitivo e as formas conjugadas irregulares. Às vezes podem ser usados sozinhos como verbos principais, e.g. “He does just as I say” (to do), “I had everything I needed” (to have), “We have never been to England” (to be).
Enquanto verbo auxiliar, o verbo “be” aparece essencialmente nas formas contínuas, e.g. “I am learning English” (to learn) e na voz passiva, e.g. “She was raised by her mother” (to raise).
“Have” pode ser usado também como um verbo auxiliar formando os tempos compostos, tais como o presente perfeito ou o passado perfeito, tanto na voz ativa quanto na voz passiva. E.g. “Have you tried to call him?” (to try), “He had been given a second chance” (to give).
Enquanto verbo auxiliar, o verbo “do” se usa para formar perguntas e frases negativas com verbos normais. Na fala, em frases negativas, “not” é usado na forma contraída “-n’t”, e.g. “Did you see that? – No, I did not / didn’t!” (to see). “Do” se usa também para enfatizar o significado de verbos normais, e.g. “Stop calling me lazy, I did clean the bathroom!” (to clean)
Os verbos modais são um tipo especial de verbos auxiliares. Esses verbos são sempre seguidos pelo infinitivo do verbo principal sem “to”, e.g. “You can leave now” (to leave), “She might know about this already” (to know).
Apenas têm uma forma e não se podem conjugar com outros auxiliares (não têm tempos contínuos nem formas passivas): não se diz “she musts”, “I am mighting” ou “you were coulded”. As formas negativas se formam adicionando “not” depois do verbo modal. Alguns modais têm formas contraídas: “can’t”, “couldn’t”, “wouldn’t”, “shouldn’t”, “won’t” e “shan’t”.
Dois verbos modais podem ser usados para indicar as formas passadas de outros verbos: can (presente) could (passado) e will (presente, futuro) would (passado).
Ênfase
do/does/did
Actually I do know that, but thanks!
Capacidade
can
be able to/am able to/are able to/is able to/was able to/were able to
could
I can read pretty fast.
She was not able to catch her plane.
Could you finish the test yesterday?
Permissão
may
might
Can I leave now?
May I come in?
Could you close the window?
Might I join you?
Proibição
cannot/can't
must not/mustn't
may not
be not to
You can't walk on the grass.
He must not fight with his sister.
You may not smoke in this room.
We are not to travel alone.
Obrigação / Ordem
must
have to/have got to
be to
will
shall
We must stay quiet.
You have to go now.
I am to stay here and wait for her.
You will stop answering back now!
You shall work harder next time.
Dever / Conselho
should
ought to
He should study more seriously.
You ought go to bed earlier.
You must see this movie once in your life!
Necessidade
have to/has to/had to
need to/needs to/needed to
He must stop complaining constantly.
I have to catch my train at 8 am.
I need to pay the rent every month.
Ausência de necessidade
do not have to/don't have to/does not have to/doesn't have to/did not have to/didn't have to
need not/needn't/needs not/do not need to/don't need to/does not need to/doesn't need to/did not need to/didn't need to/needed not
You don't have to come if you don't want to.
You needn't worry, he will be fine.
Compromisso
will/'ll
shall/'ll
I'll never lie to her again.
I shall honour this promise.
Pedido / Convite
would
Shall we dance?
Will you come to the party tonight?
Would you please help me?
Impossibilidade
could not/couldn't
will not/won't
would not/wouldn't
This can't be right.
He couldn't stop crying when he heard the news.
Regrets won't help you now!
I told you it just wouldn't work.
Certeza
That'll be him ringing the doorbell.
Probabilidade
She should be home by now.
They must be very proud.
He can't be more than thirty.
Possibilidade
He could be dead already.
It may or may not rain for the picnic.
This might be the answer to my problem.
It can be that she didn't want to bother you.
Costume
used to
I used to play in this park when I was little.
For years, she would visit her friends every Sunday.
Desafio
dare
do not dare/don't dare/does not dare/doesn't dare/daren't
did not dare/didn't dare/dared not
How dare you call me selfish?
I don't dare look down from the top.
She dared not complain about her bully.
