I could bow you could bow he could bow we could bow you could bow they could bow
V-ing form
I could be bowing you could be bowing he could be bowing we could be bowing you could be bowing they could be bowing
Perfect
I could have bowed you could have bowed he could have bowed we could have bowed you could have bowed they could have bowed
V-ing perfect
I could have been bowing you could have been bowing he could have been bowing we could have been bowing you could have been bowing they could have been bowing
Negation
Simple form
I could not bow you could not bow he could not bow we could not bow you could not bow they could not bow
V-ing form
I could not be bowing you could not be bowing he could not be bowing we could not be bowing you could not be bowing they could not be bowing
Perfect
I could not have bowed you could not have bowed he could not have bowed we could not have bowed you could not have bowed they could not have bowed
V-ing perfect
I could not have been bowing you could not have been bowing he could not have been bowing we could not have been bowing you could not have been bowing they could not have been bowing
Interrogative form
Simple form
could I bow? could you bow? could he bow? could we bow? could you bow? could they bow?
V-ing form
could I be bowing? could you be bowing? could he be bowing? could we be bowing? could you be bowing? could they be bowing?
Perfect
could I have bowed? could you have bowed? could he have bowed? could we have bowed? could you have bowed? could they have bowed?
V-ing perfect
could I have been bowing? could you have been bowing? could he have been bowing? could we have been bowing? could you have been bowing? could they have been bowing?
Interro-negative form
Simple form
could I not bow? could you not bow? could he not bow? could we not bow? could you not bow? could they not bow?
V-ing form
could I not be bowing? could you not be bowing? could he not be bowing? could we not be bowing? could you not be bowing? could they not be bowing?
Perfect
could I not have bowed? could you not have bowed? could he not have bowed? could we not have bowed? could you not have bowed? could they not have bowed?
V-ing perfect
could I not have been bowing? could you not have been bowing? could he not have been bowing? could we not have been bowing? could you not have been bowing? could they not have been bowing?