I could retrogress you could retrogress he could retrogress we could retrogress you could retrogress they could retrogress
V-ing form
I could be retrogressing you could be retrogressing he could be retrogressing we could be retrogressing you could be retrogressing they could be retrogressing
Perfect
I could have retrogressed you could have retrogressed he could have retrogressed we could have retrogressed you could have retrogressed they could have retrogressed
V-ing perfect
I could have been retrogressing you could have been retrogressing he could have been retrogressing we could have been retrogressing you could have been retrogressing they could have been retrogressing
Negation
Simple form
I could not retrogress you could not retrogress he could not retrogress we could not retrogress you could not retrogress they could not retrogress
V-ing form
I could not be retrogressing you could not be retrogressing he could not be retrogressing we could not be retrogressing you could not be retrogressing they could not be retrogressing
Perfect
I could not have retrogressed you could not have retrogressed he could not have retrogressed we could not have retrogressed you could not have retrogressed they could not have retrogressed
V-ing perfect
I could not have been retrogressing you could not have been retrogressing he could not have been retrogressing we could not have been retrogressing you could not have been retrogressing they could not have been retrogressing
Interrogative form
Simple form
could I retrogress? could you retrogress? could he retrogress? could we retrogress? could you retrogress? could they retrogress?
V-ing form
could I be retrogressing? could you be retrogressing? could he be retrogressing? could we be retrogressing? could you be retrogressing? could they be retrogressing?
Perfect
could I have retrogressed? could you have retrogressed? could he have retrogressed? could we have retrogressed? could you have retrogressed? could they have retrogressed?
V-ing perfect
could I have been retrogressing? could you have been retrogressing? could he have been retrogressing? could we have been retrogressing? could you have been retrogressing? could they have been retrogressing?
Interro-negative form
Simple form
could I not retrogress? could you not retrogress? could he not retrogress? could we not retrogress? could you not retrogress? could they not retrogress?
V-ing form
could I not be retrogressing? could you not be retrogressing? could he not be retrogressing? could we not be retrogressing? could you not be retrogressing? could they not be retrogressing?
Perfect
could I not have retrogressed? could you not have retrogressed? could he not have retrogressed? could we not have retrogressed? could you not have retrogressed? could they not have retrogressed?
V-ing perfect
could I not have been retrogressing? could you not have been retrogressing? could he not have been retrogressing? could we not have been retrogressing? could you not have been retrogressing? could they not have been retrogressing?