唯一安全的系统是关闭的，浇筑在混凝土块中，并密封在有武装警卫的铅衬房间中。
The only secure system is one that is powered off, cast in a block of concrete and sealed in a lead-lined room with armed guards.
The United States is experiencing a crisis of political decay, with institutions that are increasingly dysfunctional and unable to address the country's challenges.
衡量森林价值的真正标准不是木材的板英尺数，而是几个世纪的生态平衡。