when and how the verb 'could' can be used?

[Durra]

dear friends,

i want to know, when and how 'could' can be used?? for what kind of sentence i can use that word??

[Kitosdad]

" He wasn't sure that he could attend ".

" Surely you could have given him a lift ".

" Please, could you help me with my shopping ? "

" I never knew you could do that ! "
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Keep it simple ... Keep it interesting.

[Gray]

Yes, I could read :)
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First lesson - English, not english. I, not i. ~A student of English

[Durra]

:D thanks friends!!!