f = open('yesterday','r',encoding='utf-8')
f2 = open('yesterday.bak','w',encoding='utf-8')
old_str = input('请输入要修改的字符：')
replace_str = input('请输入替换成的字符:')
for line in f.readlines():
 line = line.replace(old_str,replace_str)
 print(line)
 f2.write(line)
f.close()
f2.close()

Somehow, it seems the love I knew was always the most destructive kind
不知为何，我经历的爱情总是最具毁灭性的的那种
Yesterday when I was young
昨日当我年少轻狂
The taste of life was sweet
生命的滋味是甜的
As rain upon my tongue
就如舌尖上的雨露