笛声

We heard the whistle of a train.

我们听到了汽笛。

I heard police sirens in the distance .

我听到警笛从远处传来。

In big cities you always hear sirens all the time.

在大城市里, 你总能听到警笛。

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

这些汽听到来近警笛便停了下来。

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

当中午笛响起时，工厂里嘈杂顿时停止了。