定时器任务用于周期性地轮询messages . php，看何时来了新的聊天项目。

A timer task is used to periodically poll messages.php to see when new chat items arrive.

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设置定时器提醒到时转换任务。

Set a timer to go off when it's time to switch tasks.

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今天，大多数的新景观灌溉系统，利用定时器和远程操作的阀门，节省园丁灌溉的转化和关闭重复的任务。

Today, most new landscape irrigation systems utilize timers and remotely operated valves, saving gardeners the repetitive task of turning irrigation on and off.

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