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