I could duplicate you could duplicate he could duplicate we could duplicate you could duplicate they could duplicate
V-ing form
I could be duplicating you could be duplicating he could be duplicating we could be duplicating you could be duplicating they could be duplicating
Perfect
I could have duplicated you could have duplicated he could have duplicated we could have duplicated you could have duplicated they could have duplicated
V-ing perfect
I could have been duplicating you could have been duplicating he could have been duplicating we could have been duplicating you could have been duplicating they could have been duplicating
Negation
Simple form
I could not duplicate you could not duplicate he could not duplicate we could not duplicate you could not duplicate they could not duplicate
V-ing form
I could not be duplicating you could not be duplicating he could not be duplicating we could not be duplicating you could not be duplicating they could not be duplicating
Perfect
I could not have duplicated you could not have duplicated he could not have duplicated we could not have duplicated you could not have duplicated they could not have duplicated
V-ing perfect
I could not have been duplicating you could not have been duplicating he could not have been duplicating we could not have been duplicating you could not have been duplicating they could not have been duplicating
Interrogative form
Simple form
could I duplicate? could you duplicate? could he duplicate? could we duplicate? could you duplicate? could they duplicate?
V-ing form
could I be duplicating? could you be duplicating? could he be duplicating? could we be duplicating? could you be duplicating? could they be duplicating?
Perfect
could I have duplicated? could you have duplicated? could he have duplicated? could we have duplicated? could you have duplicated? could they have duplicated?
V-ing perfect
could I have been duplicating? could you have been duplicating? could he have been duplicating? could we have been duplicating? could you have been duplicating? could they have been duplicating?
Interro-negative form
Simple form
could I not duplicate? could you not duplicate? could he not duplicate? could we not duplicate? could you not duplicate? could they not duplicate?
V-ing form
could I not be duplicating? could you not be duplicating? could he not be duplicating? could we not be duplicating? could you not be duplicating? could they not be duplicating?
Perfect
could I not have duplicated? could you not have duplicated? could he not have duplicated? could we not have duplicated? could you not have duplicated? could they not have duplicated?
V-ing perfect
could I not have been duplicating? could you not have been duplicating? could he not have been duplicating? could we not have been duplicating? could you not have been duplicating? could they not have been duplicating?