modals: ability, obligation,
criticism (past)
past ability:cou/d, cou/dn't, was/were ab/eto
Could /couldn't are past forms ofcan/can't. Could not is used in formai speech and writing.
Usecould /couldn't- to describe past ability.
We don't know how fast Ancient Greek athletes could run. - to describe what was allowed ar not allowed.
Women couldn't compete or watch the ancient Olympic Games.
See also Units 22 and 24 for other meanings ofcould.
We can usewas/were ableto in the place ofcould/couldn't to describe past ability in general.
He tried hard but wasn't able towin the race.
We usewas/were able to, notcould /couldn't, when we mean that we could do something and we
actually did it.
One runner feli badly, but fortunately was able tofinish the race.
past obligation: had to, didn't have to
Hadto /didn't have to /did you haveto etc are past forms ofhaveto andmust.
Usehadto- to describe past obligation, for bothmust andhave to.
Athletes who cheated in the Olympic Games hadtopay forastatue of the
god Zeus.
Of course, in ancient times athletes didn't havetotake drugs tests.
past necessity: needed to, didn't need to, needn't have
Useneeded to (regular verb) to describe what was necessary.
He needed tostop foradrink, but he kept running.
Usedidn't need to to describe what was not necessary.
In ancient Greece, winning athletes didn't need towork again.
The question form isdid you need to etc.
Useneedn't have + past participie (a form of modal verbneed) to explain that sameone did
something, but what they did was unnecessary.
I was worried because I thought that my tickets for the Games wouldn't
arrive in time. But I needn't have worried. They arrived this morninglpast criticism:shou/d have/shou/dn't have, ought tohave, ought not tohave
Useshould have/shouldn't have + past participie to criticize a past action.
'You started before the guni You shouldn't have done that.'
'But it was an accidentl' 'Well, you should have been more careful"
Useought tohave/ought not tohave+ past participle in the same way.