笛声

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

当中午的响起时，工厂里的嘈杂顿时停止了。

We heard the whistle of a train.

们听到了火车的汽。

I heard police sirens in the distance .

听到警从远处。

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

这些汽车听到的警便停了下。

In big cities you always hear sirens all the time.

在大城市里, 你总能听到警。