知之为知之,不知为不知,是知也. - To know that we know what we know,and that we do not know what we do not know,that is true knowledge.

To know that we know what we know,and that we do not know what we do not know,that is true knowledge.

知之为知之,不知为不知,是知也.

英文列表索引：A B C D E F G H I J K L M N O P Q R S T U V W Y Z

中文列表索引：A B C D E F G H I J K L M N O P Q R S T U V W Y Z