I could graduate you could graduate she could graduate we could graduate you could graduate they could graduate
V-ing form
I could be graduating you could be graduating she could be graduating we could be graduating you could be graduating they could be graduating
Perfect
I could have graduated you could have graduated she could have graduated we could have graduated you could have graduated they could have graduated
V-ing perfect
I could have been graduating you could have been graduating she could have been graduating we could have been graduating you could have been graduating they could have been graduating
Negation
Simple form
I couldn't graduate you couldn't graduate she couldn't graduate we couldn't graduate you couldn't graduate they couldn't graduate
V-ing form
I couldn't be graduating you couldn't be graduating she couldn't be graduating we couldn't be graduating you couldn't be graduating they couldn't be graduating
Perfect
I couldn't have graduated you couldn't have graduated she couldn't have graduated we couldn't have graduated you couldn't have graduated they couldn't have graduated
V-ing perfect
I couldn't have been graduating you couldn't have been graduating she couldn't have been graduating we couldn't have been graduating you couldn't have been graduating they couldn't have been graduating
Interrogative form
Simple form
could I graduate? could you graduate? could she graduate? could we graduate? could you graduate? could they graduate?
V-ing form
could I be graduating? could you be graduating? could she be graduating? could we be graduating? could you be graduating? could they be graduating?
Perfect
could I have graduated? could you have graduated? could she have graduated? could we have graduated? could you have graduated? could they have graduated?
V-ing perfect
could I have been graduating? could you have been graduating? could she have been graduating? could we have been graduating? could you have been graduating? could they have been graduating?
Interro-negative form
Simple form
couldn't I graduate? couldn't you graduate? couldn't she graduate? couldn't we graduate? couldn't you graduate? couldn't they graduate?
V-ing form
couldn't I be graduating? couldn't you be graduating? couldn't she be graduating? couldn't we be graduating? couldn't you be graduating? couldn't they be graduating?
Perfect
couldn't I have graduated? couldn't you have graduated? couldn't she have graduated? couldn't we have graduated? couldn't you have graduated? couldn't they have graduated?
V-ing perfect
couldn't I have been graduating? couldn't you have been graduating? couldn't she have been graduating? couldn't we have been graduating? couldn't you have been graduating? couldn't they have been graduating?