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