I could regret you could regret she could regret we could regret you could regret they could regret
V-ing form
I could be regreting you could be regreting she could be regreting we could be regreting you could be regreting they could be regreting
Perfect
I could have regreted you could have regreted she could have regreted we could have regreted you could have regreted they could have regreted
V-ing perfect
I could have been regreting you could have been regreting she could have been regreting we could have been regreting you could have been regreting they could have been regreting
Negation
Simple form
I could not regret you could not regret she could not regret we could not regret you could not regret they could not regret
V-ing form
I could not be regreting you could not be regreting she could not be regreting we could not be regreting you could not be regreting they could not be regreting
Perfect
I could not have regreted you could not have regreted she could not have regreted we could not have regreted you could not have regreted they could not have regreted
V-ing perfect
I could not have been regreting you could not have been regreting she could not have been regreting we could not have been regreting you could not have been regreting they could not have been regreting
Interrogative form
Simple form
could I regret? could you regret? could she regret? could we regret? could you regret? could they regret?
V-ing form
could I be regreting? could you be regreting? could she be regreting? could we be regreting? could you be regreting? could they be regreting?
Perfect
could I have regreted? could you have regreted? could she have regreted? could we have regreted? could you have regreted? could they have regreted?
V-ing perfect
could I have been regreting? could you have been regreting? could she have been regreting? could we have been regreting? could you have been regreting? could they have been regreting?
Interro-negative form
Simple form
could I not regret? could you not regret? could she not regret? could we not regret? could you not regret? could they not regret?
V-ing form
could I not be regreting? could you not be regreting? could she not be regreting? could we not be regreting? could you not be regreting? could they not be regreting?
Perfect
could I not have regreted? could you not have regreted? could she not have regreted? could we not have regreted? could you not have regreted? could they not have regreted?
V-ing perfect
could I not have been regreting? could you not have been regreting? could she not have been regreting? could we not have been regreting? could you not have been regreting? could they not have been regreting?