I could flex you could flex he could flex we could flex you could flex they could flex
V-ing form
I could be flexing you could be flexing he could be flexing we could be flexing you could be flexing they could be flexing
Perfect
I could have flexed you could have flexed he could have flexed we could have flexed you could have flexed they could have flexed
V-ing perfect
I could have been flexing you could have been flexing he could have been flexing we could have been flexing you could have been flexing they could have been flexing
Negation
Simple form
I could not flex you could not flex he could not flex we could not flex you could not flex they could not flex
V-ing form
I could not be flexing you could not be flexing he could not be flexing we could not be flexing you could not be flexing they could not be flexing
Perfect
I could not have flexed you could not have flexed he could not have flexed we could not have flexed you could not have flexed they could not have flexed
V-ing perfect
I could not have been flexing you could not have been flexing he could not have been flexing we could not have been flexing you could not have been flexing they could not have been flexing
Interrogative form
Simple form
could I flex? could you flex? could he flex? could we flex? could you flex? could they flex?
V-ing form
could I be flexing? could you be flexing? could he be flexing? could we be flexing? could you be flexing? could they be flexing?
Perfect
could I have flexed? could you have flexed? could he have flexed? could we have flexed? could you have flexed? could they have flexed?
V-ing perfect
could I have been flexing? could you have been flexing? could he have been flexing? could we have been flexing? could you have been flexing? could they have been flexing?
Interro-negative form
Simple form
could I not flex? could you not flex? could he not flex? could we not flex? could you not flex? could they not flex?
V-ing form
could I not be flexing? could you not be flexing? could he not be flexing? could we not be flexing? could you not be flexing? could they not be flexing?
Perfect
could I not have flexed? could you not have flexed? could he not have flexed? could we not have flexed? could you not have flexed? could they not have flexed?
V-ing perfect
could I not have been flexing? could you not have been flexing? could he not have been flexing? could we not have been flexing? could you not have been flexing? could they not have been flexing?