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