English verb conjugation
COULD ILLUSTRATE

Regular verb: illustrate - illustrated - illustrated

Affirmation

Simple form	V-ing form
I could illustrate you could illustrate he could illustrate we could illustrate you could illustrate they could illustrate	I could be illustrating you could be illustrating he could be illustrating we could be illustrating you could be illustrating they could be illustrating
Perfect	V-ing perfect
I could have illustrated you could have illustrated he could have illustrated we could have illustrated you could have illustrated they could have illustrated	I could have been illustrating you could have been illustrating he could have been illustrating we could have been illustrating you could have been illustrating they could have been illustrating

Negation

Simple form	V-ing form
I couldn't illustrate you couldn't illustrate he couldn't illustrate we couldn't illustrate you couldn't illustrate they couldn't illustrate	I couldn't be illustrating you couldn't be illustrating he couldn't be illustrating we couldn't be illustrating you couldn't be illustrating they couldn't be illustrating
Perfect	V-ing perfect
I couldn't have illustrated you couldn't have illustrated he couldn't have illustrated we couldn't have illustrated you couldn't have illustrated they couldn't have illustrated	I couldn't have been illustrating you couldn't have been illustrating he couldn't have been illustrating we couldn't have been illustrating you couldn't have been illustrating they couldn't have been illustrating

Interrogative form

Simple form	V-ing form
could I illustrate? could you illustrate? could he illustrate? could we illustrate? could you illustrate? could they illustrate?	could I be illustrating? could you be illustrating? could he be illustrating? could we be illustrating? could you be illustrating? could they be illustrating?
Perfect	V-ing perfect
could I have illustrated? could you have illustrated? could he have illustrated? could we have illustrated? could you have illustrated? could they have illustrated?	could I have been illustrating? could you have been illustrating? could he have been illustrating? could we have been illustrating? could you have been illustrating? could they have been illustrating?

Interro-negative form

Simple form	V-ing form
couldn't I illustrate? couldn't you illustrate? couldn't he illustrate? couldn't we illustrate? couldn't you illustrate? couldn't they illustrate?	couldn't I be illustrating? couldn't you be illustrating? couldn't he be illustrating? couldn't we be illustrating? couldn't you be illustrating? couldn't they be illustrating?
Perfect	V-ing perfect
couldn't I have illustrated? couldn't you have illustrated? couldn't he have illustrated? couldn't we have illustrated? couldn't you have illustrated? couldn't they have illustrated?	couldn't I have been illustrating? couldn't you have been illustrating? couldn't he have been illustrating? couldn't we have been illustrating? couldn't you have been illustrating? couldn't they have been illustrating?