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