I. Fill in each blank with ONE suitable word to complete the passage. (2.0 points) More than a billion people all over the world are (1) the threat of desert expansion, but few of them are aware that they themselves cause it and are also its (2) ______. People cut (3) trees for fuel and farmland. Their herd eat up the grass covering valley floors (4)______hillsides. The climate and soil quality, therefore, are affected and forests are turned into deserts. In some places, (5)_____people had to leave their homes when their wells became dry and sand buried their houses and crops. Therefore, government in nearby areas have had local people (6)__________trees and banned burning firewood for fuel. Many techniques have been (7) _______. For example, in Iran, a thin covering of oil was poured on sandy areas to retain water for planting trees, but this method may harm (8) _____ environment. Other countries built long canals or pipelines (9) water to desert areas. Unless people find more (10) methods, their homes and land will be lost. The last against the desert is continuing. 1. A. of B. in C. on D. under 2. A. victims B. enemies C. friends D. effects 3. A. off B. back C. down D. in 4. A. but B. and C. so D. when 5. A. a lot B. much C. many D. a little 6. A. planting B. plant C. to plant D. planted 7. A. using B. use C. used D. uses 8. A. the B. a C. an D. some 9. A. to carry B. take C. fetch D. bring 10. A. great B. effective C. major D. useful