I can crouch you can crouch he can crouch we can crouch you can crouch they can crouch
V-ing form
I can be crouching you can be crouching he can be crouching we can be crouching you can be crouching they can be crouching
Perfect
I can have crouched you can have crouched he can have crouched we can have crouched you can have crouched they can have crouched
V-ing perfect
I can have been crouching you can have been crouching he can have been crouching we can have been crouching you can have been crouching they can have been crouching
Negation
Simple form
I can't crouch you can't crouch he can't crouch we can't crouch you can't crouch they can't crouch
V-ing form
I can't be crouching you can't be crouching he can't be crouching we can't be crouching you can't be crouching they can't be crouching
Perfect
I can't have crouched you can't have crouched he can't have crouched we can't have crouched you can't have crouched they can't have crouched
V-ing perfect
I can't have been crouching you can't have been crouching he can't have been crouching we can't have been crouching you can't have been crouching they can't have been crouching
Interrogative form
Simple form
can I crouch? can you crouch? can he crouch? can we crouch? can you crouch? can they crouch?
V-ing form
can I be crouching? can you be crouching? can he be crouching? can we be crouching? can you be crouching? can they be crouching?
Perfect
can I have crouched? can you have crouched? can he have crouched? can we have crouched? can you have crouched? can they have crouched?
V-ing perfect
can I have been crouching? can you have been crouching? can he have been crouching? can we have been crouching? can you have been crouching? can they have been crouching?
Interro-negative form
Simple form
can't I crouch? can't you crouch? can't he crouch? can't we crouch? can't you crouch? can't they crouch?
V-ing form
can't I be crouching? can't you be crouching? can't he be crouching? can't we be crouching? can't you be crouching? can't they be crouching?
Perfect
can't I have crouched? can't you have crouched? can't he have crouched? can't we have crouched? can't you have crouched? can't they have crouched?
V-ing perfect
can't I have been crouching? can't you have been crouching? can't he have been crouching? can't we have been crouching? can't you have been crouching? can't they have been crouching?