Which of the following case meets the criteria for involuntary commitment

A．A single parent who leaves her minor children unattended and stays out all night drinking.

B．A person who lives alone and isn't able to care for himself and has schizophrenia with delusions of persecution.

C．A man who threatens to kill his wife.

D．A person with depression who says he's tired of living but doesn't have a suicide plan.

人类很早就知道城墙的防御效果，古往今来，不知上演过多少隔墙而战的攻防战役。蒙古人开始征战世界时，善于野战的游牧骑兵团对攻城战束手无策。但蒙古人善于学习，很快就掌握了攻城的战术，并将各地的攻城武器集中起来综合使用，达到了很好的效果，许多固若金汤的城池都被摧毁了。欧洲当时那些较薄的城墙，根本不能抵御蒙古人的攻击，特别是蒙古人开始使用多种威力巨大的火器，更具破坏性。从此以后，由于火炮的火力改进，城墙的作用就逐渐从人类历史中消失了。这段文字意在说明：

A．蒙古兵团是怎样征服欧洲的

B．城墙是如何退出历史舞台的

C．火器是如何在攻城战中发挥作用的

D．蒙古的游牧兵团是如何调整战术的