A cave or cavern is a hollow place in the ground, especially a natural underground space large enough for a human to enter. Caves form naturally by theweathering of rock and often extend deep underground. The word cave can also refer to much smaller openings such as sea caves, rock shelters,
วันศุกร์ที่ 12 กุมภาพันธ์ พ.ศ. 2559
Deserts
Far from being barren wastelands, deserts are biologically rich habitats with a vast array of animals and plants that have adapted to the harsh conditions there. Some deserts are among the planet's last remaining areas of total wilderness. Yet more than one billion people, one-sixth of the Earth's population, actually live in desert regions. read more
Paper
Paper is a thin material produced by pressing together moist fibres of cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets. It is a versatile material with many uses, including writing, printing, packaging, cleaning, and a number of industrial and construction processes.read more
Space
his article is about the general framework of distance and direction. For the space beyond Earth's atmosphere, see Outer space. For the keyboard key, see Space bar. For other uses, see Space (disambiguation).
Space is the boundless three-dimensional extent in which objects and events have relative position and direction.[1] Physical space is often conceived in three linear dimensions, although modern physicists usually consider it, withtime, to be part of a boundless four-dimensional continuum known as spacetime. read more
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