笛声

We heard the whistle of a train.

我们听到了火车声。

I heard police sirens in the distance .

我听到声从远处传来。

In big cities you always hear sirens all the time.

在大城市里, 你总能听到声。

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

车听到来近声便停了下来。

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

当中午声响起时，工厂里嘈杂声顿时停止了。