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 could not flank you could not flank he could not flank we could not flank you could not flank they could not flank
V-ing form
I could not be flanking you could not be flanking he could not be flanking we could not be flanking you could not be flanking they could not be flanking
Perfect
I could not have flanked you could not have flanked he could not have flanked we could not have flanked you could not have flanked they could not have flanked
V-ing perfect
I could not have been flanking you could not have been flanking he could not have been flanking we could not have been flanking you could not have been flanking they could not 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
could I not flank? could you not flank? could he not flank? could we not flank? could you not flank? could they not flank?
V-ing form
could I not be flanking? could you not be flanking? could he not be flanking? could we not be flanking? could you not be flanking? could they not be flanking?
Perfect
could I not have flanked? could you not have flanked? could he not have flanked? could we not have flanked? could you not have flanked? could they not have flanked?
V-ing perfect
could I not have been flanking? could you not have been flanking? could he not have been flanking? could we not have been flanking? could you not have been flanking? could they not have been flanking?