2.1.2 交互模式 Interactive Mode

When commands are read from a tty, the interpreter is said to be in interactive mode. In this mode it prompts for the next command with the primary prompt, usually three greater-than signs (">>> "); for continuation lines it prompts with the secondary prompt, by default three dots ("... "). The interpreter prints a welcome message stating its version number and a copyright notice before printing the first prompt:

从 tty 读取命令时，我们称解释器工作于 交互模式 。这种模式下它根据 主提示符 来执行，主提示符通常标识为三个大于号（ ">>> "）；继续的部分被称为 从属提示符 ，由三个点标识（ "... "）。在第一行之前，解释器打印欢迎信息、版本号和授权提示：

python
Python 1.5.2b2 (#1, Feb 28 1999, 00:02:06)  [GCC 2.8.1] on sunos5
Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam
>>>

Continuation lines are needed when entering a multi-line construct. As an example, take a look at this if statement:

输入多行结构时需要从属提示符了，例如，下面这个 if 语句：

>>> the_world_is_flat = 1
>>> if the_world_is_flat:
...     print "Be careful not to fall off!"
...
Be careful not to fall off!