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