I could woof you could woof she could woof we could woof you could woof they could woof
V-ing form
I could be woofing you could be woofing she could be woofing we could be woofing you could be woofing they could be woofing
Perfect
I could have woofed you could have woofed she 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 she could have been woofing we could have been woofing you could have been woofing they could have been woofing
Negation
Simple form
I could not woof you could not woof she could not woof we could not woof you could not woof they could not woof
V-ing form
I could not be woofing you could not be woofing she could not be woofing we could not be woofing you could not be woofing they could not be woofing
Perfect
I could not have woofed you could not have woofed she could not have woofed we could not have woofed you could not have woofed they could not have woofed
V-ing perfect
I could not have been woofing you could not have been woofing she could not have been woofing we could not have been woofing you could not have been woofing they could not have been woofing
Interrogative form
Simple form
could I woof? could you woof? could she woof? could we woof? could you woof? could they woof?
V-ing form
could I be woofing? could you be woofing? could she be woofing? could we be woofing? could you be woofing? could they be woofing?
Perfect
could I have woofed? could you have woofed? could she 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 she have been woofing? could we have been woofing? could you have been woofing? could they have been woofing?
Interro-negative form
Simple form
could I not woof? could you not woof? could she not woof? could we not woof? could you not woof? could they not woof?
V-ing form
could I not be woofing? could you not be woofing? could she not be woofing? could we not be woofing? could you not be woofing? could they not be woofing?
Perfect
could I not have woofed? could you not have woofed? could she not have woofed? could we not have woofed? could you not have woofed? could they not have woofed?
V-ing perfect
could I not have been woofing? could you not have been woofing? could she not have been woofing? could we not have been woofing? could you not have been woofing? could they not have been woofing?