English verb conjugation
COULD SUBSERVE

Regular verb: subserve - subserved - subserved

Affirmation

Simple form	V-ing form
I could subserve you could subserve he could subserve we could subserve you could subserve they could subserve	I could be subserving you could be subserving he could be subserving we could be subserving you could be subserving they could be subserving
Perfect	V-ing perfect
I could have subserved you could have subserved he could have subserved we could have subserved you could have subserved they could have subserved	I could have been subserving you could have been subserving he could have been subserving we could have been subserving you could have been subserving they could have been subserving

Negation

Simple form	V-ing form
I couldn't subserve you couldn't subserve he couldn't subserve we couldn't subserve you couldn't subserve they couldn't subserve	I couldn't be subserving you couldn't be subserving he couldn't be subserving we couldn't be subserving you couldn't be subserving they couldn't be subserving
Perfect	V-ing perfect
I couldn't have subserved you couldn't have subserved he couldn't have subserved we couldn't have subserved you couldn't have subserved they couldn't have subserved	I couldn't have been subserving you couldn't have been subserving he couldn't have been subserving we couldn't have been subserving you couldn't have been subserving they couldn't have been subserving

Interrogative form

Simple form	V-ing form
could I subserve? could you subserve? could he subserve? could we subserve? could you subserve? could they subserve?	could I be subserving? could you be subserving? could he be subserving? could we be subserving? could you be subserving? could they be subserving?
Perfect	V-ing perfect
could I have subserved? could you have subserved? could he have subserved? could we have subserved? could you have subserved? could they have subserved?	could I have been subserving? could you have been subserving? could he have been subserving? could we have been subserving? could you have been subserving? could they have been subserving?

Interro-negative form

Simple form	V-ing form
couldn't I subserve? couldn't you subserve? couldn't he subserve? couldn't we subserve? couldn't you subserve? couldn't they subserve?	couldn't I be subserving? couldn't you be subserving? couldn't he be subserving? couldn't we be subserving? couldn't you be subserving? couldn't they be subserving?
Perfect	V-ing perfect
couldn't I have subserved? couldn't you have subserved? couldn't he have subserved? couldn't we have subserved? couldn't you have subserved? couldn't they have subserved?	couldn't I have been subserving? couldn't you have been subserving? couldn't he have been subserving? couldn't we have been subserving? couldn't you have been subserving? couldn't they have been subserving?