concrete QueryEng of Query = {
  lincat 
    Answer, Question, Object = Str ;

  lin 
    Even x = "is" ++ x ++ "even" ;
    Odd  x = "is" ++ x ++ "odd" ;
    Prime x = "is" ++ x ++ "prime" ;
    Number n = n.s ;

    Yes = "yes" ;
    No = "no" ;

}

