I could seal you could seal he could seal we could seal you could seal they could seal
V-ing form
I could be sealing you could be sealing he could be sealing we could be sealing you could be sealing they could be sealing
Perfect
I could have sealed you could have sealed he could have sealed we could have sealed you could have sealed they could have sealed
V-ing perfect
I could have been sealing you could have been sealing he could have been sealing we could have been sealing you could have been sealing they could have been sealing
Negation
Simple form
I could not seal you could not seal he could not seal we could not seal you could not seal they could not seal
V-ing form
I could not be sealing you could not be sealing he could not be sealing we could not be sealing you could not be sealing they could not be sealing
Perfect
I could not have sealed you could not have sealed he could not have sealed we could not have sealed you could not have sealed they could not have sealed
V-ing perfect
I could not have been sealing you could not have been sealing he could not have been sealing we could not have been sealing you could not have been sealing they could not have been sealing
Interrogative form
Simple form
could I seal? could you seal? could he seal? could we seal? could you seal? could they seal?
V-ing form
could I be sealing? could you be sealing? could he be sealing? could we be sealing? could you be sealing? could they be sealing?
Perfect
could I have sealed? could you have sealed? could he have sealed? could we have sealed? could you have sealed? could they have sealed?
V-ing perfect
could I have been sealing? could you have been sealing? could he have been sealing? could we have been sealing? could you have been sealing? could they have been sealing?
Interro-negative form
Simple form
could I not seal? could you not seal? could he not seal? could we not seal? could you not seal? could they not seal?
V-ing form
could I not be sealing? could you not be sealing? could he not be sealing? could we not be sealing? could you not be sealing? could they not be sealing?
Perfect
could I not have sealed? could you not have sealed? could he not have sealed? could we not have sealed? could you not have sealed? could they not have sealed?
V-ing perfect
could I not have been sealing? could you not have been sealing? could he not have been sealing? could we not have been sealing? could you not have been sealing? could they not have been sealing?