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