could base
Regular verb: base - based- based

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could base
you could base
she could base
we could base
you could base
they could base 	I could be basing
you could be basing
she could be basing
we could be basing
you could be basing
they could be basing	I could have based
you could have based
she could have based
we could have based
you could have based
they could have based	I could have been basing
you could have been basing
she could have been basing
we could have been basing
you could have been basing
they could have been basing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't base
you couldn't base
she couldn't base
we couldn't base
you couldn't base
they couldn't base 	I couldn't be basing
you couldn't be basing
she couldn't be basing
we couldn't be basing
you couldn't be basing
they couldn't be basing	I couldn't have based
you couldn't have based
she couldn't have based
we couldn't have based
you couldn't have based
they couldn't have based	I couldn't have been basing
you couldn't have been basing
she couldn't have been basing
we couldn't have been basing
you couldn't have been basing
they couldn't have been basing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I base?
could you base?
could she base?
could we base?
could you base?
could they base? 	could I be basing?
could you be basing?
could she be basing?
could we be basing?
could you be basing?
could they be basing? 	could I have based?
could you have based?
could she have based?
could we have based?
could you have based?
could they have based? 	could I have been basing?
could you have been basing?
could she have been basing?
could we have been basing?
could you have been basing?
could they have been basing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I base?
couldn't you base?
couldn't she base?
couldn't we base?
couldn't you base?
couldn't they base? 	couldn't I be basing?
couldn't you be basing?
couldn't she be basing?
couldn't we be basing?
couldn't you be basing?
couldn't they be basing? 	couldn't I have based?
couldn't you have based?
couldn't she have based?
couldn't we have based?
couldn't you have based?
couldn't they have based? 	couldn't I have been basing?
couldn't you have been basing?
couldn't she have been basing?
couldn't we have been basing?
couldn't you have been basing?
couldn't they have been basing?