present	past	future
CAN/ CANNOT - umiejętność BE ABLE TO - pozwolenie - dedukcja [can't]	I can swim. I can't come with you. He can't be in Italy I saw her.	She was able to play the violin at the age of 5. - dedukcja; pewność She can't have written it.	Will you be able to help me tomorrow?
COULD/ COULDN'T - możliwość, prawdopodobieństwo, niepewność	He could be stuck somewhere.	- niepewność He could have had an accident. - umiejetność I could swim when I was 10.	----------
MAY/ MAY NOT - możliwość, prawdopodobieństwo, niepewność	I may not do it.	- niepewność He may have got lost.	----------
MIGHT/ MIGHT NOT - możliwość, prawdopodobieństwo, niepewność	He might win.	- niepewność He might have taken the bus.	----------
SHOULD/ SHOULDN'T - powinność - porada	He should arrive at 10. You should quit smoking.	- krytyka You should have worked harder.	-----------
OUGHT TO/ OUGHT NOT TO - to samo znaczenie co should; bardziej formalny język	I think you ought to talk to him.	- krytyka You ought to have done it better.	-----------
MUST / HAVE TO - obowiązek - konieczność MUSTN'T - nie wolno DON'T HAVE TO - nie trzeba	I must finish it today. I have to phone her. You mustn't smoke here. You don't have to turn on the heating, it's warm enough.	- obowiązek He had to do it. - dedukcja; pewność He must have left the passport at home.	I will have to talk to him.
Need - potrzebować		- brak obowiązku I didn't need to do any homework. - niepotrzebnie wykonana czynność I needn't have done any homework.