I could powder you could powder he could powder we could powder you could powder they could powder
V-ing form
I could be powdering you could be powdering he could be powdering we could be powdering you could be powdering they could be powdering
Perfect
I could have powdered you could have powdered he could have powdered we could have powdered you could have powdered they could have powdered
V-ing perfect
I could have been powdering you could have been powdering he could have been powdering we could have been powdering you could have been powdering they could have been powdering
Negation
Simple form
I couldn't powder you couldn't powder he couldn't powder we couldn't powder you couldn't powder they couldn't powder
V-ing form
I couldn't be powdering you couldn't be powdering he couldn't be powdering we couldn't be powdering you couldn't be powdering they couldn't be powdering
Perfect
I couldn't have powdered you couldn't have powdered he couldn't have powdered we couldn't have powdered you couldn't have powdered they couldn't have powdered
V-ing perfect
I couldn't have been powdering you couldn't have been powdering he couldn't have been powdering we couldn't have been powdering you couldn't have been powdering they couldn't have been powdering
Interrogative form
Simple form
could I powder? could you powder? could he powder? could we powder? could you powder? could they powder?
V-ing form
could I be powdering? could you be powdering? could he be powdering? could we be powdering? could you be powdering? could they be powdering?
Perfect
could I have powdered? could you have powdered? could he have powdered? could we have powdered? could you have powdered? could they have powdered?
V-ing perfect
could I have been powdering? could you have been powdering? could he have been powdering? could we have been powdering? could you have been powdering? could they have been powdering?
Interro-negative form
Simple form
couldn't I powder? couldn't you powder? couldn't he powder? couldn't we powder? couldn't you powder? couldn't they powder?
V-ing form
couldn't I be powdering? couldn't you be powdering? couldn't he be powdering? couldn't we be powdering? couldn't you be powdering? couldn't they be powdering?
Perfect
couldn't I have powdered? couldn't you have powdered? couldn't he have powdered? couldn't we have powdered? couldn't you have powdered? couldn't they have powdered?
V-ing perfect
couldn't I have been powdering? couldn't you have been powdering? couldn't he have been powdering? couldn't we have been powdering? couldn't you have been powdering? couldn't they have been powdering?