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