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