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