The policeman whistled for the motorcar to stop.

察令汽车停下。

I heard the wail of a police siren.

我听见的尖叫声。

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

这些汽车听到愈来愈近的声便停了下来。

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。

When he heard the police sirens, he ran off as fast as his legs could carry him.

听到响起，他拚命地跑。