I could pair you could pair he could pair we could pair you could pair they could pair
V-ing form
I could be pairing you could be pairing he could be pairing we could be pairing you could be pairing they could be pairing
Perfect
I could have paired you could have paired he could have paired we could have paired you could have paired they could have paired
V-ing perfect
I could have been pairing you could have been pairing he could have been pairing we could have been pairing you could have been pairing they could have been pairing
Negation
Simple form
I couldn't pair you couldn't pair he couldn't pair we couldn't pair you couldn't pair they couldn't pair
V-ing form
I couldn't be pairing you couldn't be pairing he couldn't be pairing we couldn't be pairing you couldn't be pairing they couldn't be pairing
Perfect
I couldn't have paired you couldn't have paired he couldn't have paired we couldn't have paired you couldn't have paired they couldn't have paired
V-ing perfect
I couldn't have been pairing you couldn't have been pairing he couldn't have been pairing we couldn't have been pairing you couldn't have been pairing they couldn't have been pairing
Interrogative form
Simple form
could I pair? could you pair? could he pair? could we pair? could you pair? could they pair?
V-ing form
could I be pairing? could you be pairing? could he be pairing? could we be pairing? could you be pairing? could they be pairing?
Perfect
could I have paired? could you have paired? could he have paired? could we have paired? could you have paired? could they have paired?
V-ing perfect
could I have been pairing? could you have been pairing? could he have been pairing? could we have been pairing? could you have been pairing? could they have been pairing?
Interro-negative form
Simple form
couldn't I pair? couldn't you pair? couldn't he pair? couldn't we pair? couldn't you pair? couldn't they pair?
V-ing form
couldn't I be pairing? couldn't you be pairing? couldn't he be pairing? couldn't we be pairing? couldn't you be pairing? couldn't they be pairing?
Perfect
couldn't I have paired? couldn't you have paired? couldn't he have paired? couldn't we have paired? couldn't you have paired? couldn't they have paired?
V-ing perfect
couldn't I have been pairing? couldn't you have been pairing? couldn't he have been pairing? couldn't we have been pairing? couldn't you have been pairing? couldn't they have been pairing?