bigFile = "File.txt"
appendTest = open(bigFile,"r",encoding="utf8")
num = 0
for i in appendTest:
num += 1
if num == 2:
i = "".join([i.strip(),"\"+被处理行！\""])
print(i.strip())
appendTest.close()
原文：https://www.cnblogs.com/surenliu/p/12830499.html