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 couldn't cough you couldn't cough she couldn't cough we couldn't cough you couldn't cough they couldn't cough
V-ing form
I couldn't be coughing you couldn't be coughing she couldn't be coughing we couldn't be coughing you couldn't be coughing they couldn't be coughing
Perfect
I couldn't have coughed you couldn't have coughed she couldn't have coughed we couldn't have coughed you couldn't have coughed they couldn't have coughed
V-ing perfect
I couldn't have been coughing you couldn't have been coughing she couldn't have been coughing we couldn't have been coughing you couldn't have been coughing they couldn't 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
couldn't I cough? couldn't you cough? couldn't she cough? couldn't we cough? couldn't you cough? couldn't they cough?
V-ing form
couldn't I be coughing? couldn't you be coughing? couldn't she be coughing? couldn't we be coughing? couldn't you be coughing? couldn't they be coughing?
Perfect
couldn't I have coughed? couldn't you have coughed? couldn't she have coughed? couldn't we have coughed? couldn't you have coughed? couldn't they have coughed?
V-ing perfect
couldn't I have been coughing? couldn't you have been coughing? couldn't she have been coughing? couldn't we have been coughing? couldn't you have been coughing? couldn't they have been coughing?