VOA慢速英语:'The Boarded Window' by Ambrose Bierce

frontier – n. a border between two countries

doorstep – n. a step or series of steps leading up to one of the doors that is used to enter or leave a building

lifeless – adj. Having no life

rifle – n. A gun that has a long barrel and that is held against your shoulder when you shoot it

unconscious – adj. not awake especially because of an injury, drug, etc.