un·grate·ful /ˌʌnˈgretfəl/
  (a.)忘恩負義的,使人不愉快的,徒勞的,討厭的
  Un·grate·ful a.
  1. Not grateful; not thankful for favors; making no returns, or making ill return for kindness, attention, etc.; ingrateful.
  2. Unpleasing; unacceptable; disagreeable; as, harsh sounds are ungrateful to the ear.
  -- Un*grate*ful*ly, adv. -- Un*grate*ful*ness, n.
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  ungrateful
       adj 1: not feeling or showing gratitude; "ungrateful heirs"; "How
              sharper than a serpent's tooth it is / To have a
              thankless child!"- Shakespeare [syn: thankless, unthankful]
              [ant: grateful]
       2: disagreeable; "I will not perform the ungrateful task of
          comparing cases of failure"- Abraham Lincoln