modal verbs
possibility
must
should
could
might
may
would
(conditional)
that must be my delivery
that should be my delivery
(pouvait/pourrait)
Obligation
must
have to
only present
had to / will have to
I decide
imposed
"I must call my mother"
"I have to do my tax return"
"I have to file my taxes"
Prohibition
mustn't
can't
NO Obligation
don't have to
"you can come if you want, but you don't have to"
Permission
can
may
(+ polite)
you may be seated
you can sit down
advice
you could
you might
should
ought to
if were you...
necessity
need
(semi-modal)
I need / he needs
I don't need / I needn't
I needn't have done it
1st conditional
If I have the time I will help you
2nd conditional
If I had the time, I would help you
3rd conditional
If I'd had the time, I would have helped you
(I could have helped you)