not know smb. from Adam

   нe знaть кoгo-л. в лицo, нe имeть ни мaлeйшeгo пpeдcтaвлeния o кoм-л.

    'Sorry to be personal,' she said quite suddenly, 'but I'm engaged...' 'To whom, Dinny?' 'Wilfred Desert, the second son of Lord Mullyon.' ...Her father's face was impassive, as was natural, for he did not know the young man from Adam (J. Galsworthy). 'Isn't that your old girl-friend over there?' 'Don't know her from Adam'