I must return the two books to the library. I _____ them for 20 days.

—I called you yesterday evening, but nobody answered the phone.  --Oh, I ___ a walk with my parents at that time.

 You’d better work in your hometown and then you can ________ your old father.

         of the surface of the earth          covered with water.

Gone with the wind is a well-known novel. She ____________ it twice.