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