I could succeed you could succeed he could succeed we could succeed you could succeed they could succeed
V-ing form
I could be succeeding you could be succeeding he could be succeeding we could be succeeding you could be succeeding they could be succeeding
Perfect
I could have succeeded you could have succeeded he could have succeeded we could have succeeded you could have succeeded they could have succeeded
V-ing perfect
I could have been succeeding you could have been succeeding he could have been succeeding we could have been succeeding you could have been succeeding they could have been succeeding
Negation
Simple form
I couldn't succeed you couldn't succeed he couldn't succeed we couldn't succeed you couldn't succeed they couldn't succeed
V-ing form
I couldn't be succeeding you couldn't be succeeding he couldn't be succeeding we couldn't be succeeding you couldn't be succeeding they couldn't be succeeding
Perfect
I couldn't have succeeded you couldn't have succeeded he couldn't have succeeded we couldn't have succeeded you couldn't have succeeded they couldn't have succeeded
V-ing perfect
I couldn't have been succeeding you couldn't have been succeeding he couldn't have been succeeding we couldn't have been succeeding you couldn't have been succeeding they couldn't have been succeeding
Interrogative form
Simple form
could I succeed? could you succeed? could he succeed? could we succeed? could you succeed? could they succeed?
V-ing form
could I be succeeding? could you be succeeding? could he be succeeding? could we be succeeding? could you be succeeding? could they be succeeding?
Perfect
could I have succeeded? could you have succeeded? could he have succeeded? could we have succeeded? could you have succeeded? could they have succeeded?
V-ing perfect
could I have been succeeding? could you have been succeeding? could he have been succeeding? could we have been succeeding? could you have been succeeding? could they have been succeeding?
Interro-negative form
Simple form
couldn't I succeed? couldn't you succeed? couldn't he succeed? couldn't we succeed? couldn't you succeed? couldn't they succeed?
V-ing form
couldn't I be succeeding? couldn't you be succeeding? couldn't he be succeeding? couldn't we be succeeding? couldn't you be succeeding? couldn't they be succeeding?
Perfect
couldn't I have succeeded? couldn't you have succeeded? couldn't he have succeeded? couldn't we have succeeded? couldn't you have succeeded? couldn't they have succeeded?
V-ing perfect
couldn't I have been succeeding? couldn't you have been succeeding? couldn't he have been succeeding? couldn't we have been succeeding? couldn't you have been succeeding? couldn't they have been succeeding?