I could regress you could regress she could regress we could regress you could regress they could regress
V-ing form
I could be regressing you could be regressing she could be regressing we could be regressing you could be regressing they could be regressing
Perfect
I could have regressed you could have regressed she could have regressed we could have regressed you could have regressed they could have regressed
V-ing perfect
I could have been regressing you could have been regressing she could have been regressing we could have been regressing you could have been regressing they could have been regressing
Negation
Simple form
I could not regress you could not regress she could not regress we could not regress you could not regress they could not regress
V-ing form
I could not be regressing you could not be regressing she could not be regressing we could not be regressing you could not be regressing they could not be regressing
Perfect
I could not have regressed you could not have regressed she could not have regressed we could not have regressed you could not have regressed they could not have regressed
V-ing perfect
I could not have been regressing you could not have been regressing she could not have been regressing we could not have been regressing you could not have been regressing they could not have been regressing
Interrogative form
Simple form
could I regress? could you regress? could she regress? could we regress? could you regress? could they regress?
V-ing form
could I be regressing? could you be regressing? could she be regressing? could we be regressing? could you be regressing? could they be regressing?
Perfect
could I have regressed? could you have regressed? could she have regressed? could we have regressed? could you have regressed? could they have regressed?
V-ing perfect
could I have been regressing? could you have been regressing? could she have been regressing? could we have been regressing? could you have been regressing? could they have been regressing?
Interro-negative form
Simple form
could I not regress? could you not regress? could she not regress? could we not regress? could you not regress? could they not regress?
V-ing form
could I not be regressing? could you not be regressing? could she not be regressing? could we not be regressing? could you not be regressing? could they not be regressing?
Perfect
could I not have regressed? could you not have regressed? could she not have regressed? could we not have regressed? could you not have regressed? could they not have regressed?
V-ing perfect
could I not have been regressing? could you not have been regressing? could she not have been regressing? could we not have been regressing? could you not have been regressing? could they not have been regressing?