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