Trench warfare is resorted to when the superior firepower of the defense compels the opposing forces to "dig in" so extensively as to sacrifice their mobility in order to gain protection.
当防守方的优势火力迫使敌方广泛“掘壕”，以牺牲机动性来获得防护力时，就会发生堑壕战。
2
Stubbornness is a defense mechanism that children adopt in order to escape their controlling parents' will.
固执是儿童采取的一种防御机制，目次是为了逃避父母的控制。
3
This latest order adds to a recent trend of the Defense Department ordering and using the unmanned systems in battle Settings.