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