Physics
Skating on ice is possible because

The surface of ice is smooth
Ice is cold
The pressure on the ice due to skate raises its melting point
The pressure on the ice due to skate melts the ice by lowering its melting point forming a thin film of water

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Physics
Superconductors are substances which

offer high resistance to the flow of current
conduct electricity at low temperature
conduct electricity at high temperatures
offer no resistance to the flow of electricity

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