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.

The pulp papermaking process is said to have been developed in China during the early 2nd century AD, possibly as early as the year 105 A.D.,^[1] by the Han court eunuch Cai Lun, althoug อ่านต่อ

Desert

      A desert is a barren area of land where little precipitation occurs and consequently living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to the processes of denudation. About one third of the land surface of the world is arid or semi-arid. This includes much of the polar regions where little precipitation occurs and which are sometimes called polar deserts or อ่านต่อ

Cave

     A cave or cavern is a hollow place in the ground,^[1][2] especially a natural underground space large enough for a human to enter. Caves form naturally by the weathering of rock and often extend deep underground. The word cave can also refer to much smaller openings such as sea caves อ่านต่อ