[root@centos7 tmp]# cat learning_python.txt 
In Python you can code;
In Python you can learn object;
In Python you can learn class.

filename = 'learning_python.txt'
with open(filename) as file_object:
  contents = file_object.read()
  print(contents.rstrip())

filename = 'learning_python.txt'
with open(filename) as file_object:
#1  contents = file_object.read()
#1  print(contents.rstrip())
  for line in file_object:
    print(line.rstrip())

filename = 'learning_python.txt'
with open(filename) as file_object:
#1  contents = file_object.read() 第一次打印，文件作为一个整体
#1  print(contents.rstrip())
#2  for line in file_object: 第二次打印，在with模块内
#2    print(line.rstrip())
  lines = file_object.readlines()
for line in lines: #第三次打印，在with模块外
  print(line.strip())