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