رد: موقع وجدت فيه أغلب الليسوننق الي يجي بامتحان ستيب(الي بتعيد معي الامتحان تدخل)
Most people think of deserts as dry ,flat areas with little vegetation and little or no rainfall ,but this hardly true .Many deserts have varled geographical formations ranging from soft ,rolling hills to stark ,jagged eliffs, and most deserts have a permanent source of water .Although desserts do not receive a high amount of rainfall-to be classified as a desert ,an area must get less than twenty –five centimeters of rain fall per year-there are money Plants that thrive on only small amounts of water and deserts are often full of such plant life.
Desert plants have a variety of mechanisms for obtaining the water needed for survival ,some plants ,such as cactus ,are able to store large amounts of water in their leaves or stems: after a rainfall these plants absorb a large supply of water to last until .the next rainfall , other plants ,such as the mesquite have extra ordinary deep root system that allow them to obtain water from far below the deserts arid surface .
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