can, can't, could, couldn't, will, won't, would, would't

[Beckliny]

Hi,

I need an enlightenment on how to use "can, can't, could, couldn't, will, won't, would, would't"

I heard someone ask, "How many people died in the ship" and the other man replied, "I couldn't tell you that"... I thought this statement should have been used in past tense not present. Why didn't he say "I can't tell you that.

Please, I need to know the differences between can, can't, could, couldn't, will, won't, would, would't, and how to use them correctly in my grammar.

Thanks.
Becky :D

[Mister Micawber]

Your main question is far too general to deal with here. Start by reading about MODAL AUXILIARY VERBS.

As to your specific case, 'could' is more polite than 'can'. Its implicit form is: 'I couldn't tell you that [if you wanted my opinion]'.
_________________
Native English teacher at Mister Micawber's

[Beckliny]

Thanks Mister. The link you gave was helpful.