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