could subserve
Regular verb: subserve - subserved- subserved

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