Chemistry
The open "Sigrees" or coal stoves often require fanning to sustain burning because of

Lack of oxygen in the surroundings of sigrees
Accumulation of smoke and dust over the sigrees
Interrupted release of moisture from the material
Tendency of carbon dioxide to form a layer along with dust smoke

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Chemistry
Water cycle refers to

Water distribution in relatively dry areas
Scientific management of water in areas excessively plagued with water-logging
An integrated attempt to recycle water in relatively arid regions
Constant movement of water from ocean to land and back to ocean once again

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