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