This is because during the five seconds that the first timer event was sleeping, the timer kept on generating Elapsed events on different worker threads.

这是因为在这5秒期间第一个定时器事件正在睡眠，而定时器却在不同的工作者线程上继续产生时间消失事件。

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The biggest difference is that System.Timers.Timer is a wrapper around Win32 waitable timer objects and raises an Elapsed event on a worker thread rather than a Tick event on the UI thread.

最大的区别就在与System.Timers.Timer类是对Win32可等待定时对象的一个包装，并在工作者线程上产生一个时间片消失事件而不是在UI线程上产生一个时间标记事件。

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For example, if the interval is set to 5 seconds and 3 seconds have already elapsed before the interval is changed to 10 seconds, the next timer event will be 13 seconds from the last timer event.

比如，设置了一个5秒的间隔，在间隔被改变为10秒时3秒已经过去了，那么下一个定时器事件将会在上一个定时器事件13秒后发生。

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