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Soap bubble
A soap bubble is a very thin film of soap water that forms a hollow sphere with an iridescent surface. Soap bubbles usually last for only a few moments and then burst either on their own or on ... > more -
Collapse of the World Trade Center
On September 11, 2001, the two main towers of the World Trade Center complex were each hit by hijacked commercial aircraft as part of the September 11, 2001 attacks. 2 WTC collapsed to the ground at ... > more -
Chemical warfare
Chemical warfare is warfare using the toxic properties of chemical substances to kill, injure or incapacitate an enemy. About 70 different chemicals have been used or stockpiled as Chemical Weapons ... > more -
Air conditioning
An air conditioner (AC or air-con) is an appliance or mechanism designed to extract heat from an area using a refrigeration cycle. In construction, a complete system of heating, ventilation and air ... > more -
Parachuting
Parachuting, or skydiving, is an activity involving the breaking of a free-fall from a height using a parachute. Today it is performed as a recreational activity and a competitive sport, as well as ... > more
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