I principali verbi modali inglesi, o modal verbs, sono can, could, may, might, must, ought to, shall, should, will, would . Ma vi sono espressioni e forme che non sono proprio modal verbs ma che sono correlate e a volte interscambiabili con essi: have to, have better, have got to...

Caratteristica dei verbi modali è che non si comportano come gli altri verbi:

• non aggiungono la -s alla terza persona singolare;
• nella forme interrogative e negative non usano l'ausiliare do;
• molti di questi non hanno una forma al futuro;
• il verbo che segue è all'infinito senza il to (a parte ought to);
• non hanno mai un complemento oggetto.

A wise man can learn more from a foolish question than a fool can learn from a wise answer.
Bruce Lee

If I could explain it to the average person, I wouldn't have been worth the Nobel Prize.
Richard Feynman

A person should set his goals as early as he can and devote all his energy and talent to getting there. With enough effort, he may achieve it. Or he may find something that is even more rewarding. But in the end, no matter what the outcome, he will know he has been alive.
Walt Disney

A son could bear complacently the death of his father while the loss of his inheritance might drive him to despair.
Niccolo Machiavelli

A human being is part of a whole, called by us the Universe, a part limited in time and space. He experiences himself, his thoughts and feelings, as something separated from the rest a kind of optical delusion of his consciousness. This delusion is a kind of prison for us, restricting us to our personal desires and to affection for a few persons nearest us. Our task must be to free ourselves from this prison by widening our circles of compassion to embrace all living creatures and the whole of nature in its beauty.
Albert Einstein

No man ought to look a given horse in the mouth.
(a caval donato non si guarda in bocca)
John Heywood