SICP 問題 2.53
(list 'a 'b 'c) (a b c) (list (list 'george)) ((george)) (cdr '((x1 x2) (y1 y2))) ((y1 y2)) (cadr '((x1 x2) (y1 y2))) (y1 y2) (pair? (car '(a short list))) #f (memq 'red '((red shoes) (blue socks))) #f (memq 'red '(red shoes blue socks)) (red shoes blue socks)