笛声

I heard police sirens in the distance .

我听声从远处传来。

We heard the whistle of a train.

我们听火车的汽声。

In big cities you always hear sirens all the time.

在大城市里, 你总能听声。

The cars had stopped at the sound of the approaching siren.

这些汽车听来近的声下来。

The din in the factory ends abruptly when the noon whistle sounds.

当中午的声响起时，工厂里的嘈杂声顿时止。