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 could not base you could not base he could not base we could not base you could not base they could not base	I could not be basing you could not be basing he could not be basing we could not be basing you could not be basing they could not be basing
Perfect	V-ing perfect
I could not have based you could not have based he could not have based we could not have based you could not have based they could not have based	I could not have been basing you could not have been basing he could not have been basing we could not have been basing you could not have been basing they could not 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
could I not base? could you not base? could he not base? could we not base? could you not base? could they not base?	could I not be basing? could you not be basing? could he not be basing? could we not be basing? could you not be basing? could they not be basing?
Perfect	V-ing perfect
could I not have based? could you not have based? could he not have based? could we not have based? could you not have based? could they not have based?	could I not have been basing? could you not have been basing? could he not have been basing? could we not have been basing? could you not have been basing? could they not have been basing?