What would the interpreter print in response to evaluating each of the following expressions?
(list 'a 'b 'c)
(list (list 'george))
(cdr '((x1 x2) (y1 y2)))
(cadr '((x1 x2) (y1 y2)))
(pair? (car '(a short list)))
(memq 'red '((red shoes) (blue socks)))
(memq 'red '(red shoes blue socks))

scheme@(guile-user)> (list 'a 'b 'c)
(a b c)
scheme@(guile-user)> (list (list 'george))
((george))
scheme@(guile-user)> (cdr '((x1 x2) (y1 y2)))
((y1 y2))
scheme@(guile-user)> (pair? (car '(a short list)))
#f
scheme@(guile-user)> (memq 'red '((red shoes) (blue socks)))
#f
scheme@(guile-user)> (memq 'red '(red shoes blue socks))
(red shoes blue socks)

Two lists are said to be equal? if they contain equal elements arranged in the same order. For
example,
(equal? '(this is a list) '(this is a list))
is true, but
(equal? '(this is a list) '(this (is a) list))
is false. To be more precise, we can define equal? recursively in terms of the basic eq? equality of
symbols by saying that a and b are equal? if they are both symbols and the symbols are eq?, or if
they are both lists such that (car a) is equal? to (car b) and (cdr a) is equal? to (cdr b). Using
this idea, implement equal? as a procedure.

(define (equal? a b)
  (if (and (pair? a)) (pair? b))
      (and (equal? (car a) (car b))
           (equal? (cdr a) (cdr b)))
      (eq? a b))

Eva Lu Ator types to the interpreter the expression
(car ''abracadabra)
To her surprise, the interpreter prints back quote. Explain.

'abracadabra 是 (quote abracadabra) 的简写形式，试看下面各个表达式的运行结果：
scheme@(guile-user)> 'abracadabra
abracadabra
scheme@(guile-user)> (quote abracadabra)
abracadabra
scheme@(guile-user)> (quote 'abracadabra)
(quote abracadabra)
scheme@(guile-user)> (quote (quote abracadabra))
(quote abracadabra)
scheme@(guile-user)> ''abracadabra
(quote abracadabra)
scheme@(guile-user)> (car ''abracadabra)
quote

• SICP-2.3.4节练习
• SICP-2.3.3节练习
• SICP-2.3.2节练习
• SICP-2.2.4节-wave代码
• SICP-2.2.4节练习

• 魔法书1.1补充：平方根算法的论证
• sicp 1.2.2 迭代的费波那契
• sicp 1.11
• 正则序和应用序
• 立方根程序