Physics
Skating on ice is possible because

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

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Physics
The earth is a

Good reflector of heat
Good absorber and good radiator of heat
Bad absorber and bad radiator of heat
Non-absorber of heat

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