I could cough you could cough she could cough we could cough you could cough they could cough
V-ing form
I could be coughing you could be coughing she could be coughing we could be coughing you could be coughing they could be coughing
Perfect
I could have coughed you could have coughed she could have coughed we could have coughed you could have coughed they could have coughed
V-ing perfect
I could have been coughing you could have been coughing she could have been coughing we could have been coughing you could have been coughing they could have been coughing
Negation
Simple form
I could not cough you could not cough she could not cough we could not cough you could not cough they could not cough
V-ing form
I could not be coughing you could not be coughing she could not be coughing we could not be coughing you could not be coughing they could not be coughing
Perfect
I could not have coughed you could not have coughed she could not have coughed we could not have coughed you could not have coughed they could not have coughed
V-ing perfect
I could not have been coughing you could not have been coughing she could not have been coughing we could not have been coughing you could not have been coughing they could not have been coughing
Interrogative form
Simple form
could I cough? could you cough? could she cough? could we cough? could you cough? could they cough?
V-ing form
could I be coughing? could you be coughing? could she be coughing? could we be coughing? could you be coughing? could they be coughing?
Perfect
could I have coughed? could you have coughed? could she have coughed? could we have coughed? could you have coughed? could they have coughed?
V-ing perfect
could I have been coughing? could you have been coughing? could she have been coughing? could we have been coughing? could you have been coughing? could they have been coughing?
Interro-negative form
Simple form
could I not cough? could you not cough? could she not cough? could we not cough? could you not cough? could they not cough?
V-ing form
could I not be coughing? could you not be coughing? could she not be coughing? could we not be coughing? could you not be coughing? could they not be coughing?
Perfect
could I not have coughed? could you not have coughed? could she not have coughed? could we not have coughed? could you not have coughed? could they not have coughed?
V-ing perfect
could I not have been coughing? could you not have been coughing? could she not have been coughing? could we not have been coughing? could you not have been coughing? could they not have been coughing?