I could foam you could foam she could foam we could foam you could foam they could foam
V-ing form
I could be foaming you could be foaming she could be foaming we could be foaming you could be foaming they could be foaming
Perfect
I could have foamed you could have foamed she could have foamed we could have foamed you could have foamed they could have foamed
V-ing perfect
I could have been foaming you could have been foaming she could have been foaming we could have been foaming you could have been foaming they could have been foaming
Negation
Simple form
I couldn't foam you couldn't foam she couldn't foam we couldn't foam you couldn't foam they couldn't foam
V-ing form
I couldn't be foaming you couldn't be foaming she couldn't be foaming we couldn't be foaming you couldn't be foaming they couldn't be foaming
Perfect
I couldn't have foamed you couldn't have foamed she couldn't have foamed we couldn't have foamed you couldn't have foamed they couldn't have foamed
V-ing perfect
I couldn't have been foaming you couldn't have been foaming she couldn't have been foaming we couldn't have been foaming you couldn't have been foaming they couldn't have been foaming
Interrogative form
Simple form
could I foam? could you foam? could she foam? could we foam? could you foam? could they foam?
V-ing form
could I be foaming? could you be foaming? could she be foaming? could we be foaming? could you be foaming? could they be foaming?
Perfect
could I have foamed? could you have foamed? could she have foamed? could we have foamed? could you have foamed? could they have foamed?
V-ing perfect
could I have been foaming? could you have been foaming? could she have been foaming? could we have been foaming? could you have been foaming? could they have been foaming?
Interro-negative form
Simple form
couldn't I foam? couldn't you foam? couldn't she foam? couldn't we foam? couldn't you foam? couldn't they foam?
V-ing form
couldn't I be foaming? couldn't you be foaming? couldn't she be foaming? couldn't we be foaming? couldn't you be foaming? couldn't they be foaming?
Perfect
couldn't I have foamed? couldn't you have foamed? couldn't she have foamed? couldn't we have foamed? couldn't you have foamed? couldn't they have foamed?
V-ing perfect
couldn't I have been foaming? couldn't you have been foaming? couldn't she have been foaming? couldn't we have been foaming? couldn't you have been foaming? couldn't they have been foaming?