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 could not illustrate you could not illustrate he could not illustrate we could not illustrate you could not illustrate they could not illustrate	I could not be illustrating you could not be illustrating he could not be illustrating we could not be illustrating you could not be illustrating they could not be illustrating
Perfect	V-ing perfect
I could not have illustrated you could not have illustrated he could not have illustrated we could not have illustrated you could not have illustrated they could not have illustrated	I could not have been illustrating you could not have been illustrating he could not have been illustrating we could not have been illustrating you could not have been illustrating they could not 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
could I not illustrate? could you not illustrate? could he not illustrate? could we not illustrate? could you not illustrate? could they not illustrate?	could I not be illustrating? could you not be illustrating? could he not be illustrating? could we not be illustrating? could you not be illustrating? could they not be illustrating?
Perfect	V-ing perfect
could I not have illustrated? could you not have illustrated? could he not have illustrated? could we not have illustrated? could you not have illustrated? could they not have illustrated?	could I not have been illustrating? could you not have been illustrating? could he not have been illustrating? could we not have been illustrating? could you not have been illustrating? could they not have been illustrating?