I could assure you could assure he could assure we could assure you could assure they could assure
V-ing form
I could be assuring you could be assuring he could be assuring we could be assuring you could be assuring they could be assuring
Perfect
I could have assured you could have assured he could have assured we could have assured you could have assured they could have assured
V-ing perfect
I could have been assuring you could have been assuring he could have been assuring we could have been assuring you could have been assuring they could have been assuring
Negation
Simple form
I could not assure you could not assure he could not assure we could not assure you could not assure they could not assure
V-ing form
I could not be assuring you could not be assuring he could not be assuring we could not be assuring you could not be assuring they could not be assuring
Perfect
I could not have assured you could not have assured he could not have assured we could not have assured you could not have assured they could not have assured
V-ing perfect
I could not have been assuring you could not have been assuring he could not have been assuring we could not have been assuring you could not have been assuring they could not have been assuring
Interrogative form
Simple form
could I assure? could you assure? could he assure? could we assure? could you assure? could they assure?
V-ing form
could I be assuring? could you be assuring? could he be assuring? could we be assuring? could you be assuring? could they be assuring?
Perfect
could I have assured? could you have assured? could he have assured? could we have assured? could you have assured? could they have assured?
V-ing perfect
could I have been assuring? could you have been assuring? could he have been assuring? could we have been assuring? could you have been assuring? could they have been assuring?
Interro-negative form
Simple form
could I not assure? could you not assure? could he not assure? could we not assure? could you not assure? could they not assure?
V-ing form
could I not be assuring? could you not be assuring? could he not be assuring? could we not be assuring? could you not be assuring? could they not be assuring?
Perfect
could I not have assured? could you not have assured? could he not have assured? could we not have assured? could you not have assured? could they not have assured?
V-ing perfect
could I not have been assuring? could you not have been assuring? could he not have been assuring? could we not have been assuring? could you not have been assuring? could they not have been assuring?