Look at that girl! Is it Susan?—No, it _______ be her. She has gone back to her hometown.
Why does Mary look so sad? – Maybe the things _______ she saw made her think of her grandmother.
Some researchers believe that there is no doubt ____ a cure for AIDS will be found.
Why not _______a taxi to go home?
____ the morning of May 2. We arrived_____ London. [ ]