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