There are some prisoners who are so dangerous to other inmates so threatening to prison guards that they must be put into the most secure of all correctional facilities.

• 有些极端危险的囚犯，对于和他们一起服刑的囚犯和看管他们的警卫都是严重的威胁。因此必须把他们置于守卫最森严的监狱，那里所有的设备都是经过特殊设计的。