他们家有一套防盗警报系统保护。

Their home is protected by a ___system of burglar alarms.

整栋房子都由中央供暖系统供暖。

The whole house is warmed by a central-heating ___system.

音乐厅的新音响系统能产生清澈透亮的音效。

The concert hall's new sound ___system produces crystal-clear audio.