2017届北京市高考英语一轮复习综合练习：30 （含解析）_高考复习指南

2017届北京市高考英语一轮复习综合练习：30 （含解析）

　　C. to offer assistance D. to ask forgiveness

　　Hawaii is an important trading center and about six million tourists visit there every year. With all that traffic in and out, exotic species(外来物种）have plenty of opportunities to reach the islands. According to biologists, exotic species are the number one threat to the state' s economy, environment, and way of life.

　　The question in Hawaii is, can the invaders be stopped？

　　Quarantines are one way to do this. Quarantine is the process of isolating animals or products. In Hawaii, pet dogs and cats coming into the state remain in a special holding facility for four months to make sure they don’ t have rabies(狂犬病） Many agricultural products are also quarantined to see if they are carrying insect pests or plant diseases.

　　Inspection is a second way to stop biological invaders. At airports, borders, and shipping ports, inspectors examine passengers and their baggage to see if they are carrying exotic species. The inspectors also destroy fruits, vegetables, or other goods that might be carrying harmful pests or diseases. Specially trained dogs also smell goods in the ship for exotic species.

　　What if an exotic species slips by inspectors? Then efforts are made to control the invader. In Hawaii，government agencies control invaders by setting

　　livetraps around wildlife shelters and other places. At Haleakala National Park employees have built miles of fences to keep out exotic pigs and goats. For years these animals ate and walked over native rain forest plants, hut the fences have helped reverse(逆转）this damage. Now native plants grow in places that were bare rock only a short time ago.