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