7.4 � � ˨ � � � � � ӵ Ľ ṹ � � �

7.4.1 � � � � � � � ӵ Ľ ṹ Ҫ � �

� � � � � � � � � � � � � ʱ � � � � � ˱ � � � � � ǿ � ȼ � � � � � ȷ � � � � � � � � � Ӽ � � � ֱ � � � ⣻ ͬ ʱ � � Ӧ � � � � � ȷ � � � � � ӵ Ľ ṹ � ͽ ṹ � ߴ 硣
� � � � � � � ӵ � � � ʽ Ӧ � � � � � � � Ӽ � � ľ � � � ṹ � � � � � � � � � ӵ Ļ � � � � � � � ȷ � � � �

7.4.2 � � � � � � ˨ � � � ӳ � � � ƫ � � � غ �

7.4.3 � � ֤ � 㹻 � İ � � ֿ ռ �

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