I can flex you can flex she can flex we can flex you can flex they can flex
V-ing form
I can be flexing you can be flexing she can be flexing we can be flexing you can be flexing they can be flexing
Perfect
I can have flexed you can have flexed she can have flexed we can have flexed you can have flexed they can have flexed
V-ing perfect
I can have been flexing you can have been flexing she can have been flexing we can have been flexing you can have been flexing they can have been flexing
Negation
Simple form
I can't flex you can't flex she can't flex we can't flex you can't flex they can't flex
V-ing form
I can't be flexing you can't be flexing she can't be flexing we can't be flexing you can't be flexing they can't be flexing
Perfect
I can't have flexed you can't have flexed she can't have flexed we can't have flexed you can't have flexed they can't have flexed
V-ing perfect
I can't have been flexing you can't have been flexing she can't have been flexing we can't have been flexing you can't have been flexing they can't have been flexing
Interrogative form
Simple form
can I flex? can you flex? can she flex? can we flex? can you flex? can they flex?
V-ing form
can I be flexing? can you be flexing? can she be flexing? can we be flexing? can you be flexing? can they be flexing?
Perfect
can I have flexed? can you have flexed? can she have flexed? can we have flexed? can you have flexed? can they have flexed?
V-ing perfect
can I have been flexing? can you have been flexing? can she have been flexing? can we have been flexing? can you have been flexing? can they have been flexing?
Interro-negative form
Simple form
can't I flex? can't you flex? can't she flex? can't we flex? can't you flex? can't they flex?
V-ing form
can't I be flexing? can't you be flexing? can't she be flexing? can't we be flexing? can't you be flexing? can't they be flexing?
Perfect
can't I have flexed? can't you have flexed? can't she have flexed? can't we have flexed? can't you have flexed? can't they have flexed?
V-ing perfect
can't I have been flexing? can't you have been flexing? can't she have been flexing? can't we have been flexing? can't you have been flexing? can't they have been flexing?