English verb conjugation
COULD BASE

Regular verb: base - based - based

Affirmation

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