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