raj.txt的内容：

one line
two line
three line
four line
five line
six line
seven line
eight line
nine line
ten line

代码：

with open('raj.txt','r') as f:
    size = 10
    f_contents = f.read(size)
    print(f_contents,end='*')
    print(f.tell())
    f_contents = f.read(size)
    print(f_contents,end='*')
    print(f.tell())

输出：

    one line
    t*11
    wo line
    th*22