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