Many deserts were formed 8000 to 10000 years ago. Some are very hot in the day. In fact the ______ temperature ever recorded on Earth was 56.6 in California and Nevada's Death Valley in 1913. Even though many deserts can reach temperatures of over 37.8 during the day in summer, they can get cold at night. ______ is that? In most places, clouds and water vapor (水蒸气) hold in heat, but deserts don't have enough clouds and water vapor to do this.

Some deserts are always cold-in fact the biggest desert in the world is Antarctica (南极洲)! ______ it's covered in snow and ice, it seldom rains or snows in Antarctica, which ______ it a desert.

It may seem like ______ can live in a desert because it's so dry. But most deserts are full of ______, with plants and animals that have adapted to (适应) live without much water. Some plants, like cacti, store enough water in their stems (茎) to last until the next rain. Other plants, like grass, have very small leaves that curl up (卷起) in the daytime ______ the water they have.

Desert animals also adapted to live ______ much water. Kangaroo rats in the Sonoran Desert get water from the seeds they eat. Most desert animals stay underground or under rocks during the day. Many of them _______   for food at night, when it's cool.

If you plan to go to a desert, be sure to pack water, sunscreen, and protective clothing. ______, you are not a kangaroo rat!

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