AUXILIAR MODAL COULD = ( PODIA O PODRIA )

Afirmativa.-
Sujeto + Could + Verbo + Complemento.
My grandmother could speak english.


Negativa.-
Sujeto + Could + not + Verbo + Complemento.
My grandmother could not speak english.


Interrogativa.-
Could + sujeto + verbo + complemento + ?
Could my grandmother speak english?