The policeman whistled for the motorcar to stop.

警察吹警令汽车停。

I heard the wail of a police siren.

听见警的尖叫声。

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

这些汽车听到愈愈近的警声便停了。

I heard police sirens in the distance .

听到警声从远。

In big cities you always hear sirens all the time.

在大城市里, 你总能听到警声。

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

听到警响起，他拚命地跑。