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 couldn't remark you couldn't remark he couldn't remark we couldn't remark you couldn't remark they couldn't remark
V-ing form
I couldn't be remarking you couldn't be remarking he couldn't be remarking we couldn't be remarking you couldn't be remarking they couldn't be remarking
Perfect
I couldn't have remarked you couldn't have remarked he couldn't have remarked we couldn't have remarked you couldn't have remarked they couldn't have remarked
V-ing perfect
I couldn't have been remarking you couldn't have been remarking he couldn't have been remarking we couldn't have been remarking you couldn't have been remarking they couldn't 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
couldn't I remark? couldn't you remark? couldn't he remark? couldn't we remark? couldn't you remark? couldn't they remark?
V-ing form
couldn't I be remarking? couldn't you be remarking? couldn't he be remarking? couldn't we be remarking? couldn't you be remarking? couldn't they be remarking?
Perfect
couldn't I have remarked? couldn't you have remarked? couldn't he have remarked? couldn't we have remarked? couldn't you have remarked? couldn't they have remarked?
V-ing perfect
couldn't I have been remarking? couldn't you have been remarking? couldn't he have been remarking? couldn't we have been remarking? couldn't you have been remarking? couldn't they have been remarking?