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 couldn't bow you couldn't bow he couldn't bow we couldn't bow you couldn't bow they couldn't bow
V-ing form
I couldn't be bowing you couldn't be bowing he couldn't be bowing we couldn't be bowing you couldn't be bowing they couldn't be bowing
Perfect
I couldn't have bowed you couldn't have bowed he couldn't have bowed we couldn't have bowed you couldn't have bowed they couldn't have bowed
V-ing perfect
I couldn't have been bowing you couldn't have been bowing he couldn't have been bowing we couldn't have been bowing you couldn't have been bowing they couldn't 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
couldn't I bow? couldn't you bow? couldn't he bow? couldn't we bow? couldn't you bow? couldn't they bow?
V-ing form
couldn't I be bowing? couldn't you be bowing? couldn't he be bowing? couldn't we be bowing? couldn't you be bowing? couldn't they be bowing?
Perfect
couldn't I have bowed? couldn't you have bowed? couldn't he have bowed? couldn't we have bowed? couldn't you have bowed? couldn't they have bowed?
V-ing perfect
couldn't I have been bowing? couldn't you have been bowing? couldn't he have been bowing? couldn't we have been bowing? couldn't you have been bowing? couldn't they have been bowing?