English verb conjugation
COULD FLOSS

Regular verb: floss - flossed - flossed

Affirmation

Simple form	V-ing form
I could floss you could floss he could floss we could floss you could floss they could floss	I could be flossing you could be flossing he could be flossing we could be flossing you could be flossing they could be flossing
Perfect	V-ing perfect
I could have flossed you could have flossed he could have flossed we could have flossed you could have flossed they could have flossed	I could have been flossing you could have been flossing he could have been flossing we could have been flossing you could have been flossing they could have been flossing

Negation

Simple form	V-ing form
I could not floss you could not floss he could not floss we could not floss you could not floss they could not floss	I could not be flossing you could not be flossing he could not be flossing we could not be flossing you could not be flossing they could not be flossing
Perfect	V-ing perfect
I could not have flossed you could not have flossed he could not have flossed we could not have flossed you could not have flossed they could not have flossed	I could not have been flossing you could not have been flossing he could not have been flossing we could not have been flossing you could not have been flossing they could not have been flossing

Interrogative form

Simple form	V-ing form
could I floss? could you floss? could he floss? could we floss? could you floss? could they floss?	could I be flossing? could you be flossing? could he be flossing? could we be flossing? could you be flossing? could they be flossing?
Perfect	V-ing perfect
could I have flossed? could you have flossed? could he have flossed? could we have flossed? could you have flossed? could they have flossed?	could I have been flossing? could you have been flossing? could he have been flossing? could we have been flossing? could you have been flossing? could they have been flossing?

Interro-negative form

Simple form	V-ing form
could I not floss? could you not floss? could he not floss? could we not floss? could you not floss? could they not floss?	could I not be flossing? could you not be flossing? could he not be flossing? could we not be flossing? could you not be flossing? could they not be flossing?
Perfect	V-ing perfect
could I not have flossed? could you not have flossed? could he not have flossed? could we not have flossed? could you not have flossed? could they not have flossed?	could I not have been flossing? could you not have been flossing? could he not have been flossing? could we not have been flossing? could you not have been flossing? could they not have been flossing?