I could flock you could flock he could flock we could flock you could flock they could flock
V-ing form
I could be flocking you could be flocking he could be flocking we could be flocking you could be flocking they could be flocking
Perfect
I could have flocked you could have flocked he could have flocked we could have flocked you could have flocked they could have flocked
V-ing perfect
I could have been flocking you could have been flocking he could have been flocking we could have been flocking you could have been flocking they could have been flocking
Negation
Simple form
I could not flock you could not flock he could not flock we could not flock you could not flock they could not flock
V-ing form
I could not be flocking you could not be flocking he could not be flocking we could not be flocking you could not be flocking they could not be flocking
Perfect
I could not have flocked you could not have flocked he could not have flocked we could not have flocked you could not have flocked they could not have flocked
V-ing perfect
I could not have been flocking you could not have been flocking he could not have been flocking we could not have been flocking you could not have been flocking they could not have been flocking
Interrogative form
Simple form
could I flock? could you flock? could he flock? could we flock? could you flock? could they flock?
V-ing form
could I be flocking? could you be flocking? could he be flocking? could we be flocking? could you be flocking? could they be flocking?
Perfect
could I have flocked? could you have flocked? could he have flocked? could we have flocked? could you have flocked? could they have flocked?
V-ing perfect
could I have been flocking? could you have been flocking? could he have been flocking? could we have been flocking? could you have been flocking? could they have been flocking?
Interro-negative form
Simple form
could I not flock? could you not flock? could he not flock? could we not flock? could you not flock? could they not flock?
V-ing form
could I not be flocking? could you not be flocking? could he not be flocking? could we not be flocking? could you not be flocking? could they not be flocking?
Perfect
could I not have flocked? could you not have flocked? could he not have flocked? could we not have flocked? could you not have flocked? could they not have flocked?
V-ing perfect
could I not have been flocking? could you not have been flocking? could he not have been flocking? could we not have been flocking? could you not have been flocking? could they not have been flocking?