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。

youdao

One girl tried to call her mum with her mobile phone but there was no signal in the mountain area.

一个女孩试图打电话给她妈妈和她的手机，但在山区没有信号。

youdao

Yes, it's a small mountain village. My cellphone couldn't receive signal there.

是的，是一个小山村。我的手机在那里收不到信号。

youdao