I could swear you could swear she could swear we could swear you could swear they could swear
V-ing form
I could be swearing you could be swearing she could be swearing we could be swearing you could be swearing they could be swearing
Perfect
I could have sworn you could have sworn she could have sworn we could have sworn you could have sworn they could have sworn
V-ing perfect
I could have been swearing you could have been swearing she could have been swearing we could have been swearing you could have been swearing they could have been swearing
Negation
Simple form
I couldn't swear you couldn't swear she couldn't swear we couldn't swear you couldn't swear they couldn't swear
V-ing form
I couldn't be swearing you couldn't be swearing she couldn't be swearing we couldn't be swearing you couldn't be swearing they couldn't be swearing
Perfect
I couldn't have sworn you couldn't have sworn she couldn't have sworn we couldn't have sworn you couldn't have sworn they couldn't have sworn
V-ing perfect
I couldn't have been swearing you couldn't have been swearing she couldn't have been swearing we couldn't have been swearing you couldn't have been swearing they couldn't have been swearing
Interrogative form
Simple form
could I swear? could you swear? could she swear? could we swear? could you swear? could they swear?
V-ing form
could I be swearing? could you be swearing? could she be swearing? could we be swearing? could you be swearing? could they be swearing?
Perfect
could I have sworn? could you have sworn? could she have sworn? could we have sworn? could you have sworn? could they have sworn?
V-ing perfect
could I have been swearing? could you have been swearing? could she have been swearing? could we have been swearing? could you have been swearing? could they have been swearing?
Interro-negative form
Simple form
couldn't I swear? couldn't you swear? couldn't she swear? couldn't we swear? couldn't you swear? couldn't they swear?
V-ing form
couldn't I be swearing? couldn't you be swearing? couldn't she be swearing? couldn't we be swearing? couldn't you be swearing? couldn't they be swearing?
Perfect
couldn't I have sworn? couldn't you have sworn? couldn't she have sworn? couldn't we have sworn? couldn't you have sworn? couldn't they have sworn?
V-ing perfect
couldn't I have been swearing? couldn't you have been swearing? couldn't she have been swearing? couldn't we have been swearing? couldn't you have been swearing? couldn't they have been swearing?