I could bus you could bus she could bus we could bus you could bus they could bus
V-ing form
I could be bussing you could be bussing she could be bussing we could be bussing you could be bussing they could be bussing
Perfect
I could have bussed you could have bussed she 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 she could have been bussing we could have been bussing you could have been bussing they could have been bussing
Negation
Simple form
I couldn't bus you couldn't bus she couldn't bus we couldn't bus you couldn't bus they couldn't bus
V-ing form
I couldn't be bussing you couldn't be bussing she couldn't be bussing we couldn't be bussing you couldn't be bussing they couldn't be bussing
Perfect
I couldn't have bussed you couldn't have bussed she couldn't have bussed we couldn't have bussed you couldn't have bussed they couldn't have bussed
V-ing perfect
I couldn't have been bussing you couldn't have been bussing she couldn't have been bussing we couldn't have been bussing you couldn't have been bussing they couldn't have been bussing
Interrogative form
Simple form
could I bus? could you bus? could she bus? could we bus? could you bus? could they bus?
V-ing form
could I be bussing? could you be bussing? could she be bussing? could we be bussing? could you be bussing? could they be bussing?
Perfect
could I have bussed? could you have bussed? could she 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 she have been bussing? could we have been bussing? could you have been bussing? could they have been bussing?
Interro-negative form
Simple form
couldn't I bus? couldn't you bus? couldn't she bus? couldn't we bus? couldn't you bus? couldn't they bus?
V-ing form
couldn't I be bussing? couldn't you be bussing? couldn't she be bussing? couldn't we be bussing? couldn't you be bussing? couldn't they be bussing?
Perfect
couldn't I have bussed? couldn't you have bussed? couldn't she have bussed? couldn't we have bussed? couldn't you have bussed? couldn't they have bussed?
V-ing perfect
couldn't I have been bussing? couldn't you have been bussing? couldn't she have been bussing? couldn't we have been bussing? couldn't you have been bussing? couldn't they have been bussing?