I could remark you could remark he could remark we could remark you could remark they could remark
V-ing form
I could be remarking you could be remarking he could be remarking we could be remarking you could be remarking they could be remarking
Perfect
I could have remarked you could have remarked he could have remarked we could have remarked you could have remarked they could have remarked
V-ing perfect
I could have been remarking you could have been remarking he could have been remarking we could have been remarking you could have been remarking they could have been remarking
Negation
Simple form
I could not remark you could not remark he could not remark we could not remark you could not remark they could not remark
V-ing form
I could not be remarking you could not be remarking he could not be remarking we could not be remarking you could not be remarking they could not be remarking
Perfect
I could not have remarked you could not have remarked he could not have remarked we could not have remarked you could not have remarked they could not have remarked
V-ing perfect
I could not have been remarking you could not have been remarking he could not have been remarking we could not have been remarking you could not have been remarking they could not have been remarking
Interrogative form
Simple form
could I remark? could you remark? could he remark? could we remark? could you remark? could they remark?
V-ing form
could I be remarking? could you be remarking? could he be remarking? could we be remarking? could you be remarking? could they be remarking?
Perfect
could I have remarked? could you have remarked? could he have remarked? could we have remarked? could you have remarked? could they have remarked?
V-ing perfect
could I have been remarking? could you have been remarking? could he have been remarking? could we have been remarking? could you have been remarking? could they have been remarking?
Interro-negative form
Simple form
could I not remark? could you not remark? could he not remark? could we not remark? could you not remark? could they not remark?
V-ing form
could I not be remarking? could you not be remarking? could he not be remarking? could we not be remarking? could you not be remarking? could they not be remarking?
Perfect
could I not have remarked? could you not have remarked? could he not have remarked? could we not have remarked? could you not have remarked? could they not have remarked?
V-ing perfect
could I not have been remarking? could you not have been remarking? could he not have been remarking? could we not have been remarking? could you not have been remarking? could they not have been remarking?