如何在python中读取和拆分一个txt文件中的行，并复制到一个新的txt文件中？

source_file = open('source.txt', 'r')
target_file = open('target.txt', 'w')

for line in source_file:
    target_file.write(line)

source_file.close()
target_file.close()

source_file = open('source.txt', 'r')
target_file = open('target.txt', 'w')

for line in source_file:
    target_file.write(line)

source_file.close()
target_file.close()