English verb conjugation
COULD DO

Irregular verb: do - did - done

Affirmation

Simple form	V-ing form
I could do you could do he could do we could do you could do they could do	I could be doing you could be doing he could be doing we could be doing you could be doing they could be doing
Perfect	V-ing perfect
I could have done you could have done he could have done we could have done you could have done they could have done	I could have been doing you could have been doing he could have been doing we could have been doing you could have been doing they could have been doing

Negation

Simple form	V-ing form
I couldn't do you couldn't do he couldn't do we couldn't do you couldn't do they couldn't do	I couldn't be doing you couldn't be doing he couldn't be doing we couldn't be doing you couldn't be doing they couldn't be doing
Perfect	V-ing perfect
I couldn't have done you couldn't have done he couldn't have done we couldn't have done you couldn't have done they couldn't have done	I couldn't have been doing you couldn't have been doing he couldn't have been doing we couldn't have been doing you couldn't have been doing they couldn't have been doing

Interrogative form

Simple form	V-ing form
could I do? could you do? could he do? could we do? could you do? could they do?	could I be doing? could you be doing? could he be doing? could we be doing? could you be doing? could they be doing?
Perfect	V-ing perfect
could I have done? could you have done? could he have done? could we have done? could you have done? could they have done?	could I have been doing? could you have been doing? could he have been doing? could we have been doing? could you have been doing? could they have been doing?

Interro-negative form

Simple form	V-ing form
couldn't I do? couldn't you do? couldn't he do? couldn't we do? couldn't you do? couldn't they do?	couldn't I be doing? couldn't you be doing? couldn't he be doing? couldn't we be doing? couldn't you be doing? couldn't they be doing?
Perfect	V-ing perfect
couldn't I have done? couldn't you have done? couldn't he have done? couldn't we have done? couldn't you have done? couldn't they have done?	couldn't I have been doing? couldn't you have been doing? couldn't he have been doing? couldn't we have been doing? couldn't you have been doing? couldn't they have been doing?