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