I could download you could download he could download we could download you could download they could download
V-ing form
I could be downloading you could be downloading he could be downloading we could be downloading you could be downloading they could be downloading
Perfect
I could have downloaded you could have downloaded he could have downloaded we could have downloaded you could have downloaded they could have downloaded
V-ing perfect
I could have been downloading you could have been downloading he could have been downloading we could have been downloading you could have been downloading they could have been downloading
Negation
Simple form
I could not download you could not download he could not download we could not download you could not download they could not download
V-ing form
I could not be downloading you could not be downloading he could not be downloading we could not be downloading you could not be downloading they could not be downloading
Perfect
I could not have downloaded you could not have downloaded he could not have downloaded we could not have downloaded you could not have downloaded they could not have downloaded
V-ing perfect
I could not have been downloading you could not have been downloading he could not have been downloading we could not have been downloading you could not have been downloading they could not have been downloading
Interrogative form
Simple form
could I download? could you download? could he download? could we download? could you download? could they download?
V-ing form
could I be downloading? could you be downloading? could he be downloading? could we be downloading? could you be downloading? could they be downloading?
Perfect
could I have downloaded? could you have downloaded? could he have downloaded? could we have downloaded? could you have downloaded? could they have downloaded?
V-ing perfect
could I have been downloading? could you have been downloading? could he have been downloading? could we have been downloading? could you have been downloading? could they have been downloading?
Interro-negative form
Simple form
could I not download? could you not download? could he not download? could we not download? could you not download? could they not download?
V-ing form
could I not be downloading? could you not be downloading? could he not be downloading? could we not be downloading? could you not be downloading? could they not be downloading?
Perfect
could I not have downloaded? could you not have downloaded? could he not have downloaded? could we not have downloaded? could you not have downloaded? could they not have downloaded?
V-ing perfect
could I not have been downloading? could you not have been downloading? could he not have been downloading? could we not have been downloading? could you not have been downloading? could they not have been downloading?