I could cross you could cross she could cross we could cross you could cross they could cross
V-ing form
I could be crossing you could be crossing she could be crossing we could be crossing you could be crossing they could be crossing
Perfect
I could have crossed you could have crossed she could have crossed we could have crossed you could have crossed they could have crossed
V-ing perfect
I could have been crossing you could have been crossing she could have been crossing we could have been crossing you could have been crossing they could have been crossing
Negation
Simple form
I could not cross you could not cross she could not cross we could not cross you could not cross they could not cross
V-ing form
I could not be crossing you could not be crossing she could not be crossing we could not be crossing you could not be crossing they could not be crossing
Perfect
I could not have crossed you could not have crossed she could not have crossed we could not have crossed you could not have crossed they could not have crossed
V-ing perfect
I could not have been crossing you could not have been crossing she could not have been crossing we could not have been crossing you could not have been crossing they could not have been crossing
Interrogative form
Simple form
could I cross? could you cross? could she cross? could we cross? could you cross? could they cross?
V-ing form
could I be crossing? could you be crossing? could she be crossing? could we be crossing? could you be crossing? could they be crossing?
Perfect
could I have crossed? could you have crossed? could she have crossed? could we have crossed? could you have crossed? could they have crossed?
V-ing perfect
could I have been crossing? could you have been crossing? could she have been crossing? could we have been crossing? could you have been crossing? could they have been crossing?
Interro-negative form
Simple form
could I not cross? could you not cross? could she not cross? could we not cross? could you not cross? could they not cross?
V-ing form
could I not be crossing? could you not be crossing? could she not be crossing? could we not be crossing? could you not be crossing? could they not be crossing?
Perfect
could I not have crossed? could you not have crossed? could she not have crossed? could we not have crossed? could you not have crossed? could they not have crossed?
V-ing perfect
could I not have been crossing? could you not have been crossing? could she not have been crossing? could we not have been crossing? could you not have been crossing? could they not have been crossing?