English verb conjugation
COULD CURTAIN

Regular verb: curtain - curtained - curtained

Affirmation

Simple form	V-ing form
I could curtain you could curtain he could curtain we could curtain you could curtain they could curtain	I could be curtaining you could be curtaining he could be curtaining we could be curtaining you could be curtaining they could be curtaining
Perfect	V-ing perfect
I could have curtained you could have curtained he could have curtained we could have curtained you could have curtained they could have curtained	I could have been curtaining you could have been curtaining he could have been curtaining we could have been curtaining you could have been curtaining they could have been curtaining

Negation

Simple form	V-ing form
I couldn't curtain you couldn't curtain he couldn't curtain we couldn't curtain you couldn't curtain they couldn't curtain	I couldn't be curtaining you couldn't be curtaining he couldn't be curtaining we couldn't be curtaining you couldn't be curtaining they couldn't be curtaining
Perfect	V-ing perfect
I couldn't have curtained you couldn't have curtained he couldn't have curtained we couldn't have curtained you couldn't have curtained they couldn't have curtained	I couldn't have been curtaining you couldn't have been curtaining he couldn't have been curtaining we couldn't have been curtaining you couldn't have been curtaining they couldn't have been curtaining

Interrogative form

Simple form	V-ing form
could I curtain? could you curtain? could he curtain? could we curtain? could you curtain? could they curtain?	could I be curtaining? could you be curtaining? could he be curtaining? could we be curtaining? could you be curtaining? could they be curtaining?
Perfect	V-ing perfect
could I have curtained? could you have curtained? could he have curtained? could we have curtained? could you have curtained? could they have curtained?	could I have been curtaining? could you have been curtaining? could he have been curtaining? could we have been curtaining? could you have been curtaining? could they have been curtaining?

Interro-negative form

Simple form	V-ing form
couldn't I curtain? couldn't you curtain? couldn't he curtain? couldn't we curtain? couldn't you curtain? couldn't they curtain?	couldn't I be curtaining? couldn't you be curtaining? couldn't he be curtaining? couldn't we be curtaining? couldn't you be curtaining? couldn't they be curtaining?
Perfect	V-ing perfect
couldn't I have curtained? couldn't you have curtained? couldn't he have curtained? couldn't we have curtained? couldn't you have curtained? couldn't they have curtained?	couldn't I have been curtaining? couldn't you have been curtaining? couldn't he have been curtaining? couldn't we have been curtaining? couldn't you have been curtaining? couldn't they have been curtaining?