I could begin you could begin he could begin we could begin you could begin they could begin
V-ing form
I could be beginning you could be beginning he could be beginning we could be beginning you could be beginning they could be beginning
Perfect
I could have begun you could have begun he could have begun we could have begun you could have begun they could have begun
V-ing perfect
I could have been beginning you could have been beginning he could have been beginning we could have been beginning you could have been beginning they could have been beginning
Negation
Simple form
I could not begin you could not begin he could not begin we could not begin you could not begin they could not begin
V-ing form
I could not be beginning you could not be beginning he could not be beginning we could not be beginning you could not be beginning they could not be beginning
Perfect
I could not have begun you could not have begun he could not have begun we could not have begun you could not have begun they could not have begun
V-ing perfect
I could not have been beginning you could not have been beginning he could not have been beginning we could not have been beginning you could not have been beginning they could not have been beginning
Interrogative form
Simple form
could I begin? could you begin? could he begin? could we begin? could you begin? could they begin?
V-ing form
could I be beginning? could you be beginning? could he be beginning? could we be beginning? could you be beginning? could they be beginning?
Perfect
could I have begun? could you have begun? could he have begun? could we have begun? could you have begun? could they have begun?
V-ing perfect
could I have been beginning? could you have been beginning? could he have been beginning? could we have been beginning? could you have been beginning? could they have been beginning?
Interro-negative form
Simple form
could I not begin? could you not begin? could he not begin? could we not begin? could you not begin? could they not begin?
V-ing form
could I not be beginning? could you not be beginning? could he not be beginning? could we not be beginning? could you not be beginning? could they not be beginning?
Perfect
could I not have begun? could you not have begun? could he not have begun? could we not have begun? could you not have begun? could they not have begun?
V-ing perfect
could I not have been beginning? could you not have been beginning? could he not have been beginning? could we not have been beginning? could you not have been beginning? could they not have been beginning?