What do you think of when you hear the word "desert"? We usually think of deserts as hot, dry places. In fact, there are both hot and cold deserts in the world. Scientists defined deserts as areas of land where there are less than ten inches of rainfalls per year and there are few plants. ＿＿（26）＿＿ Precipitation is almost always frozen in the form of ice or snow. ＿＿（27）＿＿ So these regions are considered deserts and given the special label "cold deserts." The low temperature there ranges from 10 to 50°F. in summer and from -50 to 10°F. in winter. ＿＿（28）＿＿ As with cold deserts, there is usually little water available for plant growth. But contrary to what many people think, hot deserts are not lifeless wastelands. ＿＿（29）＿＿ These species have learned to adapt to the lack of water and harsh temperatures. Also, they are not necessarily made up of endless shifting sand dunes. ＿＿（30）＿＿ Some deserts have steep, rocky mountains, while others are flat.