You may think there is only sand in the desert of the world.（21）, it is not true. In the desert, as we know, there is only a little （22）, far from enough for most plants. Still we can see some plants in the desert. There is water in some places in the desert. We（23） these places oases（绿洲）. In the oases , there are villages and towns. People grow crops in the fields there. They have camels, sheep and other animals. These animals depend（24）the desert plants for their food and do not need （25）water. The（26） are useful to the desert people in many ways. They eat the meat and drink the milk of the animals. They use the camels for carrying water, food , tents and something else. The people in the desert have to keep （27） from place to place. They must always look for grass or desert plants for their animals to eat. When there is no more food for their animals, they move to 28 place. The desert people are very （29）. No man in the desert would ever refuse （30）the people in trouble or give them food and water.