We have done things we ought not to have done and ________ undone things we ought to have done.

　　A. left　　　　　　　　　　　　　B. leave

　　C. will leave　　　　　　　　　　 D. leaving

We have done things we ought not to have done and ________ undone things we ought to have done.

　　A. left　　　　　　　　　　　　　B. leave

　　C. will leave　　　　　　　　　　 D. leaving

We have done things we ought not to have done and ________ undone         things we ought to have done.

We have done things we ought not to have done and ________ undone         things we ought to have done.

We have done things we ought not to have done and ______ undone things we ought to have done.