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