I could bus you could bus he could bus we could bus you could bus they could bus
V-ing form
I could be bussing you could be bussing he could be bussing we could be bussing you could be bussing they could be bussing
Perfect
I could have bussed you could have bussed he could have bussed we could have bussed you could have bussed they could have bussed
V-ing perfect
I could have been bussing you could have been bussing he could have been bussing we could have been bussing you could have been bussing they could have been bussing
Negation
Simple form
I could not bus you could not bus he could not bus we could not bus you could not bus they could not bus
V-ing form
I could not be bussing you could not be bussing he could not be bussing we could not be bussing you could not be bussing they could not be bussing
Perfect
I could not have bussed you could not have bussed he could not have bussed we could not have bussed you could not have bussed they could not have bussed
V-ing perfect
I could not have been bussing you could not have been bussing he could not have been bussing we could not have been bussing you could not have been bussing they could not have been bussing
Interrogative form
Simple form
could I bus? could you bus? could he bus? could we bus? could you bus? could they bus?
V-ing form
could I be bussing? could you be bussing? could he be bussing? could we be bussing? could you be bussing? could they be bussing?
Perfect
could I have bussed? could you have bussed? could he have bussed? could we have bussed? could you have bussed? could they have bussed?
V-ing perfect
could I have been bussing? could you have been bussing? could he have been bussing? could we have been bussing? could you have been bussing? could they have been bussing?
Interro-negative form
Simple form
could I not bus? could you not bus? could he not bus? could we not bus? could you not bus? could they not bus?
V-ing form
could I not be bussing? could you not be bussing? could he not be bussing? could we not be bussing? could you not be bussing? could they not be bussing?
Perfect
could I not have bussed? could you not have bussed? could he not have bussed? could we not have bussed? could you not have bussed? could they not have bussed?
V-ing perfect
could I not have been bussing? could you not have been bussing? could he not have been bussing? could we not have been bussing? could you not have been bussing? could they not have been bussing?