The bomber, the machine-gun, the long-range gun and poison gas are developments of the spear, while the air-raid shelter, the steel helmet, the concrete fortification and the gas mask are developments of the shield.

• 轰炸机、机关枪、远射程炮、毒气，是矛的发展；防空掩蔽部、钢盔、水泥工事、防毒面具，是盾的发展。