air-raid shelter
2.Investigation on the Abandoned Air-Raid Shelter and Study on the Stability of Wall Rock
4.This paper discusses elimination of disturbance, detection of air-raid shelter, check up of road surface and lining quality of channel and detection of karst cave.
5.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.


