gated nature of signal

例句：

1. 1. The gates of the palace were always open to visitors.
   宫殿的大门总是对游客开放。
2. 2. The prison was gated and only allowed a few people in at a time.
   监狱是上锁的，一次只允许几个人进入。
3. 3.The company's policy is to gated access to its facilities.
   该公司的政策是严格控制其设施的访问。