I could celebrate you could celebrate he could celebrate we could celebrate you could celebrate they could celebrate
V-ing form
I could be celebrating you could be celebrating he could be celebrating we could be celebrating you could be celebrating they could be celebrating
Perfect
I could have celebrated you could have celebrated he could have celebrated we could have celebrated you could have celebrated they could have celebrated
V-ing perfect
I could have been celebrating you could have been celebrating he could have been celebrating we could have been celebrating you could have been celebrating they could have been celebrating
Negation
Simple form
I couldn't celebrate you couldn't celebrate he couldn't celebrate we couldn't celebrate you couldn't celebrate they couldn't celebrate
V-ing form
I couldn't be celebrating you couldn't be celebrating he couldn't be celebrating we couldn't be celebrating you couldn't be celebrating they couldn't be celebrating
Perfect
I couldn't have celebrated you couldn't have celebrated he couldn't have celebrated we couldn't have celebrated you couldn't have celebrated they couldn't have celebrated
V-ing perfect
I couldn't have been celebrating you couldn't have been celebrating he couldn't have been celebrating we couldn't have been celebrating you couldn't have been celebrating they couldn't have been celebrating
Interrogative form
Simple form
could I celebrate? could you celebrate? could he celebrate? could we celebrate? could you celebrate? could they celebrate?
V-ing form
could I be celebrating? could you be celebrating? could he be celebrating? could we be celebrating? could you be celebrating? could they be celebrating?
Perfect
could I have celebrated? could you have celebrated? could he have celebrated? could we have celebrated? could you have celebrated? could they have celebrated?
V-ing perfect
could I have been celebrating? could you have been celebrating? could he have been celebrating? could we have been celebrating? could you have been celebrating? could they have been celebrating?
Interro-negative form
Simple form
couldn't I celebrate? couldn't you celebrate? couldn't he celebrate? couldn't we celebrate? couldn't you celebrate? couldn't they celebrate?
V-ing form
couldn't I be celebrating? couldn't you be celebrating? couldn't he be celebrating? couldn't we be celebrating? couldn't you be celebrating? couldn't they be celebrating?
Perfect
couldn't I have celebrated? couldn't you have celebrated? couldn't he have celebrated? couldn't we have celebrated? couldn't you have celebrated? couldn't they have celebrated?
V-ing perfect
couldn't I have been celebrating? couldn't you have been celebrating? couldn't he have been celebrating? couldn't we have been celebrating? couldn't you have been celebrating? couldn't they have been celebrating?