I could crab you could crab she could crab we could crab you could crab they could crab
V-ing form
I could be crabbing you could be crabbing she could be crabbing we could be crabbing you could be crabbing they could be crabbing
Perfect
I could have crabbed you could have crabbed she could have crabbed we could have crabbed you could have crabbed they could have crabbed
V-ing perfect
I could have been crabbing you could have been crabbing she could have been crabbing we could have been crabbing you could have been crabbing they could have been crabbing
Negation
Simple form
I could not crab you could not crab she could not crab we could not crab you could not crab they could not crab
V-ing form
I could not be crabbing you could not be crabbing she could not be crabbing we could not be crabbing you could not be crabbing they could not be crabbing
Perfect
I could not have crabbed you could not have crabbed she could not have crabbed we could not have crabbed you could not have crabbed they could not have crabbed
V-ing perfect
I could not have been crabbing you could not have been crabbing she could not have been crabbing we could not have been crabbing you could not have been crabbing they could not have been crabbing
Interrogative form
Simple form
could I crab? could you crab? could she crab? could we crab? could you crab? could they crab?
V-ing form
could I be crabbing? could you be crabbing? could she be crabbing? could we be crabbing? could you be crabbing? could they be crabbing?
Perfect
could I have crabbed? could you have crabbed? could she have crabbed? could we have crabbed? could you have crabbed? could they have crabbed?
V-ing perfect
could I have been crabbing? could you have been crabbing? could she have been crabbing? could we have been crabbing? could you have been crabbing? could they have been crabbing?
Interro-negative form
Simple form
could I not crab? could you not crab? could she not crab? could we not crab? could you not crab? could they not crab?
V-ing form
could I not be crabbing? could you not be crabbing? could she not be crabbing? could we not be crabbing? could you not be crabbing? could they not be crabbing?
Perfect
could I not have crabbed? could you not have crabbed? could she not have crabbed? could we not have crabbed? could you not have crabbed? could they not have crabbed?
V-ing perfect
could I not have been crabbing? could you not have been crabbing? could she not have been crabbing? could we not have been crabbing? could you not have been crabbing? could they not have been crabbing?