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 cannot crouch you cannot crouch he cannot crouch we cannot crouch you cannot crouch they cannot crouch
V-ing form
I cannot be crouching you cannot be crouching he cannot be crouching we cannot be crouching you cannot be crouching they cannot be crouching
Perfect
I cannot have crouched you cannot have crouched he cannot have crouched we cannot have crouched you cannot have crouched they cannot have crouched
V-ing perfect
I cannot have been crouching you cannot have been crouching he cannot have been crouching we cannot have been crouching you cannot have been crouching they cannot 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 I not crouch? can you not crouch? can he not crouch? can we not crouch? can you not crouch? can they not crouch?
V-ing form
can I not be crouching? can you not be crouching? can he not be crouching? can we not be crouching? can you not be crouching? can they not be crouching?
Perfect
can I not have crouched? can you not have crouched? can he not have crouched? can we not have crouched? can you not have crouched? can they not have crouched?
V-ing perfect
can I not have been crouching? can you not have been crouching? can he not have been crouching? can we not have been crouching? can you not have been crouching? can they not have been crouching?