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 couldn't floss you couldn't floss he couldn't floss we couldn't floss you couldn't floss they couldn't floss	I couldn't be flossing you couldn't be flossing he couldn't be flossing we couldn't be flossing you couldn't be flossing they couldn't be flossing
Perfect	V-ing perfect
I couldn't have flossed you couldn't have flossed he couldn't have flossed we couldn't have flossed you couldn't have flossed they couldn't have flossed	I couldn't have been flossing you couldn't have been flossing he couldn't have been flossing we couldn't have been flossing you couldn't have been flossing they couldn't 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
couldn't I floss? couldn't you floss? couldn't he floss? couldn't we floss? couldn't you floss? couldn't they floss?	couldn't I be flossing? couldn't you be flossing? couldn't he be flossing? couldn't we be flossing? couldn't you be flossing? couldn't they be flossing?
Perfect	V-ing perfect
couldn't I have flossed? couldn't you have flossed? couldn't he have flossed? couldn't we have flossed? couldn't you have flossed? couldn't they have flossed?	couldn't I have been flossing? couldn't you have been flossing? couldn't he have been flossing? couldn't we have been flossing? couldn't you have been flossing? couldn't they have been flossing?