Each user needs a keyboard for input and a screen for output.
用户需要一个键盘进行输入，一个显示器进行输出。
By default, standard input is read from the keyboard, while standard output and standard error are printed to the screen.
默认情况下，标准输入从键盘读取，同时标准输出和标准错误会打印到屏幕。
By default, standard input is read from the keyboard, while standard output and standard error are printed to the screen.
默认情况下，标准输入从键盘读取，同时标准输出和标准错误会打印到屏幕。
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