I could database you could database he could database we could database you could database they could database
V-ing form
I could be databasing you could be databasing he could be databasing we could be databasing you could be databasing they could be databasing
Perfect
I could have databased you could have databased he could have databased we could have databased you could have databased they could have databased
V-ing perfect
I could have been databasing you could have been databasing he could have been databasing we could have been databasing you could have been databasing they could have been databasing
Negation
Simple form
I could not database you could not database he could not database we could not database you could not database they could not database
V-ing form
I could not be databasing you could not be databasing he could not be databasing we could not be databasing you could not be databasing they could not be databasing
Perfect
I could not have databased you could not have databased he could not have databased we could not have databased you could not have databased they could not have databased
V-ing perfect
I could not have been databasing you could not have been databasing he could not have been databasing we could not have been databasing you could not have been databasing they could not have been databasing
Interrogative form
Simple form
could I database? could you database? could he database? could we database? could you database? could they database?
V-ing form
could I be databasing? could you be databasing? could he be databasing? could we be databasing? could you be databasing? could they be databasing?
Perfect
could I have databased? could you have databased? could he have databased? could we have databased? could you have databased? could they have databased?
V-ing perfect
could I have been databasing? could you have been databasing? could he have been databasing? could we have been databasing? could you have been databasing? could they have been databasing?
Interro-negative form
Simple form
could I not database? could you not database? could he not database? could we not database? could you not database? could they not database?
V-ing form
could I not be databasing? could you not be databasing? could he not be databasing? could we not be databasing? could you not be databasing? could they not be databasing?
Perfect
could I not have databased? could you not have databased? could he not have databased? could we not have databased? could you not have databased? could they not have databased?
V-ing perfect
could I not have been databasing? could you not have been databasing? could he not have been databasing? could we not have been databasing? could you not have been databasing? could they not have been databasing?