Analogous to a snow avalanche on a steep mountain slope, an incoming light pulse initially frees just a few charge carriers which in turn free others until the original signal is amplified many times.

像陡峭山坡上的雪崩一样，一束入射光的脉冲最初仅仅释放少数的电荷载子(charge carrier)，这些电荷载子再轮流释放其他的载子，直到原始信号被放大很多次。

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Berea College in Kentucky offers laptops to all of its incoming students. And if your computer breaks during matriculation, the university will repair it free of charge.

肯塔基州的伯里亚学院为所有新生提供笔记本电脑，如果电脑在入学考试期间坏了，学校还会免费维修。

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Fake calls is an application which with you can fake incoming phone calls, no actual call is made thus the calls are free of charge.

假冒电话是一个应用程序，你可以用假进料电话，没有任何实际的电话是如此的电话都是免费的。

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