I could extract you could extract she could extract we could extract you could extract they could extract
V-ing form
I could be extracting you could be extracting she could be extracting we could be extracting you could be extracting they could be extracting
Perfect
I could have extracted you could have extracted she could have extracted we could have extracted you could have extracted they could have extracted
V-ing perfect
I could have been extracting you could have been extracting she could have been extracting we could have been extracting you could have been extracting they could have been extracting
Negation
Simple form
I could not extract you could not extract she could not extract we could not extract you could not extract they could not extract
V-ing form
I could not be extracting you could not be extracting she could not be extracting we could not be extracting you could not be extracting they could not be extracting
Perfect
I could not have extracted you could not have extracted she could not have extracted we could not have extracted you could not have extracted they could not have extracted
V-ing perfect
I could not have been extracting you could not have been extracting she could not have been extracting we could not have been extracting you could not have been extracting they could not have been extracting
Interrogative form
Simple form
could I extract? could you extract? could she extract? could we extract? could you extract? could they extract?
V-ing form
could I be extracting? could you be extracting? could she be extracting? could we be extracting? could you be extracting? could they be extracting?
Perfect
could I have extracted? could you have extracted? could she have extracted? could we have extracted? could you have extracted? could they have extracted?
V-ing perfect
could I have been extracting? could you have been extracting? could she have been extracting? could we have been extracting? could you have been extracting? could they have been extracting?
Interro-negative form
Simple form
could I not extract? could you not extract? could she not extract? could we not extract? could you not extract? could they not extract?
V-ing form
could I not be extracting? could you not be extracting? could she not be extracting? could we not be extracting? could you not be extracting? could they not be extracting?
Perfect
could I not have extracted? could you not have extracted? could she not have extracted? could we not have extracted? could you not have extracted? could they not have extracted?
V-ing perfect
could I not have been extracting? could you not have been extracting? could she not have been extracting? could we not have been extracting? could you not have been extracting? could they not have been extracting?