I could backstop you could backstop he could backstop we could backstop you could backstop they could backstop
V-ing form
I could be backstoping you could be backstoping he could be backstoping we could be backstoping you could be backstoping they could be backstoping
Perfect
I could have backstoped you could have backstoped he could have backstoped we could have backstoped you could have backstoped they could have backstoped
V-ing perfect
I could have been backstoping you could have been backstoping he could have been backstoping we could have been backstoping you could have been backstoping they could have been backstoping
Negation
Simple form
I could not backstop you could not backstop he could not backstop we could not backstop you could not backstop they could not backstop
V-ing form
I could not be backstoping you could not be backstoping he could not be backstoping we could not be backstoping you could not be backstoping they could not be backstoping
Perfect
I could not have backstoped you could not have backstoped he could not have backstoped we could not have backstoped you could not have backstoped they could not have backstoped
V-ing perfect
I could not have been backstoping you could not have been backstoping he could not have been backstoping we could not have been backstoping you could not have been backstoping they could not have been backstoping
Interrogative form
Simple form
could I backstop? could you backstop? could he backstop? could we backstop? could you backstop? could they backstop?
V-ing form
could I be backstoping? could you be backstoping? could he be backstoping? could we be backstoping? could you be backstoping? could they be backstoping?
Perfect
could I have backstoped? could you have backstoped? could he have backstoped? could we have backstoped? could you have backstoped? could they have backstoped?
V-ing perfect
could I have been backstoping? could you have been backstoping? could he have been backstoping? could we have been backstoping? could you have been backstoping? could they have been backstoping?
Interro-negative form
Simple form
could I not backstop? could you not backstop? could he not backstop? could we not backstop? could you not backstop? could they not backstop?
V-ing form
could I not be backstoping? could you not be backstoping? could he not be backstoping? could we not be backstoping? could you not be backstoping? could they not be backstoping?
Perfect
could I not have backstoped? could you not have backstoped? could he not have backstoped? could we not have backstoped? could you not have backstoped? could they not have backstoped?
V-ing perfect
could I not have been backstoping? could you not have been backstoping? could he not have been backstoping? could we not have been backstoping? could you not have been backstoping? could they not have been backstoping?