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