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 can't flock you can't flock he can't flock we can't flock you can't flock they can't flock
V-ing form
I can't be flocking you can't be flocking he can't be flocking we can't be flocking you can't be flocking they can't be flocking
Perfect
I can't have flocked you can't have flocked he can't have flocked we can't have flocked you can't have flocked they can't have flocked
V-ing perfect
I can't have been flocking you can't have been flocking he can't have been flocking we can't have been flocking you can't have been flocking they can't 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't I flock? can't you flock? can't he flock? can't we flock? can't you flock? can't they flock?
V-ing form
can't I be flocking? can't you be flocking? can't he be flocking? can't we be flocking? can't you be flocking? can't they be flocking?
Perfect
can't I have flocked? can't you have flocked? can't he have flocked? can't we have flocked? can't you have flocked? can't they have flocked?
V-ing perfect
can't I have been flocking? can't you have been flocking? can't he have been flocking? can't we have been flocking? can't you have been flocking? can't they have been flocking?