I could blank you could blank she could blank we could blank you could blank they could blank
V-ing form
I could be blanking you could be blanking she could be blanking we could be blanking you could be blanking they could be blanking
Perfect
I could have blanked you could have blanked she could have blanked we could have blanked you could have blanked they could have blanked
V-ing perfect
I could have been blanking you could have been blanking she could have been blanking we could have been blanking you could have been blanking they could have been blanking
Negation
Simple form
I could not blank you could not blank she could not blank we could not blank you could not blank they could not blank
V-ing form
I could not be blanking you could not be blanking she could not be blanking we could not be blanking you could not be blanking they could not be blanking
Perfect
I could not have blanked you could not have blanked she could not have blanked we could not have blanked you could not have blanked they could not have blanked
V-ing perfect
I could not have been blanking you could not have been blanking she could not have been blanking we could not have been blanking you could not have been blanking they could not have been blanking
Interrogative form
Simple form
could I blank? could you blank? could she blank? could we blank? could you blank? could they blank?
V-ing form
could I be blanking? could you be blanking? could she be blanking? could we be blanking? could you be blanking? could they be blanking?
Perfect
could I have blanked? could you have blanked? could she have blanked? could we have blanked? could you have blanked? could they have blanked?
V-ing perfect
could I have been blanking? could you have been blanking? could she have been blanking? could we have been blanking? could you have been blanking? could they have been blanking?
Interro-negative form
Simple form
could I not blank? could you not blank? could she not blank? could we not blank? could you not blank? could they not blank?
V-ing form
could I not be blanking? could you not be blanking? could she not be blanking? could we not be blanking? could you not be blanking? could they not be blanking?
Perfect
could I not have blanked? could you not have blanked? could she not have blanked? could we not have blanked? could you not have blanked? could they not have blanked?
V-ing perfect
could I not have been blanking? could you not have been blanking? could she not have been blanking? could we not have been blanking? could you not have been blanking? could they not have been blanking?