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