English verb conjugation
COULD ADD

Regular verb: add - added - added

Affirmation

Simple form	V-ing form
I could add you could add she could add we could add you could add they could add	I could be adding you could be adding she could be adding we could be adding you could be adding they could be adding
Perfect	V-ing perfect
I could have added you could have added she could have added we could have added you could have added they could have added	I could have been adding you could have been adding she could have been adding we could have been adding you could have been adding they could have been adding

Negation

Simple form	V-ing form
I could not add you could not add she could not add we could not add you could not add they could not add	I could not be adding you could not be adding she could not be adding we could not be adding you could not be adding they could not be adding
Perfect	V-ing perfect
I could not have added you could not have added she could not have added we could not have added you could not have added they could not have added	I could not have been adding you could not have been adding she could not have been adding we could not have been adding you could not have been adding they could not have been adding

Interrogative form

Simple form	V-ing form
could I add? could you add? could she add? could we add? could you add? could they add?	could I be adding? could you be adding? could she be adding? could we be adding? could you be adding? could they be adding?
Perfect	V-ing perfect
could I have added? could you have added? could she have added? could we have added? could you have added? could they have added?	could I have been adding? could you have been adding? could she have been adding? could we have been adding? could you have been adding? could they have been adding?

Interro-negative form

Simple form	V-ing form
could I not add? could you not add? could she not add? could we not add? could you not add? could they not add?	could I not be adding? could you not be adding? could she not be adding? could we not be adding? could you not be adding? could they not be adding?
Perfect	V-ing perfect
could I not have added? could you not have added? could she not have added? could we not have added? could you not have added? could they not have added?	could I not have been adding? could you not have been adding? could she not have been adding? could we not have been adding? could you not have been adding? could they not have been adding?