English verb conjugation
COULD SUPPLEMENT

Regular verb: supplement - supplemented - supplemented

Affirmation

Simple form	V-ing form
I could supplement you could supplement he could supplement we could supplement you could supplement they could supplement	I could be supplementing you could be supplementing he could be supplementing we could be supplementing you could be supplementing they could be supplementing
Perfect	V-ing perfect
I could have supplemented you could have supplemented he could have supplemented we could have supplemented you could have supplemented they could have supplemented	I could have been supplementing you could have been supplementing he could have been supplementing we could have been supplementing you could have been supplementing they could have been supplementing

Negation

Simple form	V-ing form
I couldn't supplement you couldn't supplement he couldn't supplement we couldn't supplement you couldn't supplement they couldn't supplement	I couldn't be supplementing you couldn't be supplementing he couldn't be supplementing we couldn't be supplementing you couldn't be supplementing they couldn't be supplementing
Perfect	V-ing perfect
I couldn't have supplemented you couldn't have supplemented he couldn't have supplemented we couldn't have supplemented you couldn't have supplemented they couldn't have supplemented	I couldn't have been supplementing you couldn't have been supplementing he couldn't have been supplementing we couldn't have been supplementing you couldn't have been supplementing they couldn't have been supplementing

Interrogative form

Simple form	V-ing form
could I supplement? could you supplement? could he supplement? could we supplement? could you supplement? could they supplement?	could I be supplementing? could you be supplementing? could he be supplementing? could we be supplementing? could you be supplementing? could they be supplementing?
Perfect	V-ing perfect
could I have supplemented? could you have supplemented? could he have supplemented? could we have supplemented? could you have supplemented? could they have supplemented?	could I have been supplementing? could you have been supplementing? could he have been supplementing? could we have been supplementing? could you have been supplementing? could they have been supplementing?

Interro-negative form

Simple form	V-ing form
couldn't I supplement? couldn't you supplement? couldn't he supplement? couldn't we supplement? couldn't you supplement? couldn't they supplement?	couldn't I be supplementing? couldn't you be supplementing? couldn't he be supplementing? couldn't we be supplementing? couldn't you be supplementing? couldn't they be supplementing?
Perfect	V-ing perfect
couldn't I have supplemented? couldn't you have supplemented? couldn't he have supplemented? couldn't we have supplemented? couldn't you have supplemented? couldn't they have supplemented?	couldn't I have been supplementing? couldn't you have been supplementing? couldn't he have been supplementing? couldn't we have been supplementing? couldn't you have been supplementing? couldn't they have been supplementing?