English verb conjugation
COULD ADD

Regular verb: add - added - added

Affirmation

Simple form	V-ing form
I could add you could add he could add we could add you could add they could add	I could be adding you could be adding he 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 he 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 he 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 couldn't add you couldn't add he couldn't add we couldn't add you couldn't add they couldn't add	I couldn't be adding you couldn't be adding he couldn't be adding we couldn't be adding you couldn't be adding they couldn't be adding
Perfect	V-ing perfect
I couldn't have added you couldn't have added he couldn't have added we couldn't have added you couldn't have added they couldn't have added	I couldn't have been adding you couldn't have been adding he couldn't have been adding we couldn't have been adding you couldn't have been adding they couldn't have been adding

Interrogative form

Simple form	V-ing form
could I add? could you add? could he add? could we add? could you add? could they add?	could I be adding? could you be adding? could he 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 he 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 he 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
couldn't I add? couldn't you add? couldn't he add? couldn't we add? couldn't you add? couldn't they add?	couldn't I be adding? couldn't you be adding? couldn't he be adding? couldn't we be adding? couldn't you be adding? couldn't they be adding?
Perfect	V-ing perfect
couldn't I have added? couldn't you have added? couldn't he have added? couldn't we have added? couldn't you have added? couldn't they have added?	couldn't I have been adding? couldn't you have been adding? couldn't he have been adding? couldn't we have been adding? couldn't you have been adding? couldn't they have been adding?