Verbi ausiliari, o verbi utili, sono di solito usati insieme al verbo principale per conferire un significato specifico alla frase. Possono anche essere usati per coniugare i verbi nei tempicomposti, per chiedere e rispondere alle domande sì-no o per esprimere la negazione e la voce passiva.
I tre verbi ausiliari più comuni, “be”, “have” e “do”, sono chiamati ausiliari primari.
Come i verbi ordinari, i verbi ausiliari hanno sia le forme all'infinito che le forme irregolari coniugate. A volte possono essere usati da soli come verbi principali, ad esempio “He does just as I say” (to do), “I had everything I needed” (to have), “We have never been to England” (to be).
Come ausiliare, “be” viene utilizzato principalmente per le forme continue, ad es. “I am learning English” (to learn) e per le forme passive, ad esempio “She was raised by her mother” (to raise).
“Have” è utilizzato anche come ausiliare per formare tempi composti come il presente o il passato perfetto (past perfect), sia nella voce attiva che in quella passiva. Ad esempio “Have you tried to call him?” (to try), “He had been given a second chance” (to give).
“Do” è utilizzato come ausiliario per formare domande e frasi negative con verbi ordinari. Nella forma negativa all'orale, “not” è contratto e cambia in “-n’t”, ad esempio “Did you see that? – No, I did not / didn’t!” (to see). “Do” può essere utilizzato insieme ai verbi ordinari anche per dare più enfasi, ad esempio “Stop calling me lazy, I did clean the bathroom!” (to clean)
I verbi modali sono un tipo speciale di verbi ausiliari. Sono sempre seguiti dall'infinito di un verbo principale senza "to", ad esempio “You can leave now” (to leave), “She might know about this already” (to know).
I modali hanno una sola forma e non possono essere coniugati con altri ausiliari (niente tempi continui o forme passive): non si può dire “she musts”, “I am mighting” o “you were coulded”. Le forme negative si formano aggiungendo "not" dopo il verbo modale. Alcuni modali possono essere contratti: “can’t”, “couldn’t”, “wouldn’t”, “shouldn’t”, “won’t” e “shan’t”.
Due modali possono essere utilizzati per formare il passato di altri: can (presente) could (passato) e will (presente, futuro) would (passato).
Enfasi
do/does/did
Actually I do know that, but thanks!
Capacità
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?
Permesso
may
might
Can I leave now?
May I come in?
Could you close the window?
Might I join you?
Divieto
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.
Obbligo / Ordine
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.
Dovere / Consiglio
should
ought to
He should study more seriously.
You ought go to bed earlier.
You must see this movie once in your life!
Necessità
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.
Assenza di necessità
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.
Impegno
will/'ll
shall/'ll
I'll never lie to her again.
I shall honour this promise.
Richiesta / Invito
would
Shall we dance?
Will you come to the party tonight?
Would you please help me?
Impossibilità
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.
Certezza
That'll be him ringing the doorbell.
Probabilità
She should be home by now.
They must be very proud.
He can't be more than thirty.
Possibilità
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.
Abitudine
used to
I used to play in this park when I was little.
For years, she would visit her friends every Sunday.
Osare
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.
