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