For more than 500 years the book has been a remarkably stable entity: a coherent string of connected words, printed on paper and bound between covers.
500多年来，书一直是相当稳定的物体：由具有条理的字符串连而成，被印在纸上，有封面和封底。
2
Therefore, to determine the potential distribution of insulator string is very important to detect the poor insulator and safety and stable operation of transmission line.