（新课标）2015届高考英语二轮复习 专题限时训练 史地自然型阅读理解（一）.docVIP

　[史地自然型阅读理解(一)] (限时：25分钟) 　　　　　　　　　　　　　　　　 (一) Bees add an estimated eighteen billion dollars a year to the value of American crops. They pollinate(授粉)flowers that become fruits, nuts and vegetables. But, in recent years, honeybee colonies in the United States and Europe have been shrinking. Scientists have proposed different theories to explain what is known as colony collapse disorder. New research suggests that a commonly used group of insecticide(杀虫剂) could cause bees to have a hard time finding their way back to their hive. The new research looks at the use of pesticides called neonicotinoids. They were first used in the 1990s. They are now put on the seeds of many major crops around the world. The seedlings absorb the chemicals as they grow. That means farmers do not need to spray a whole field. Instead there is a little bit of insecticide inside each plant—including the pollen(花粉) and the nectar(花蜜) that the bees want. There is not enough pesticide to kill them. But the new research in the journal Science says it may harm them anyway. Researchers stuck microchips to the backs of the bees. These chips recorded the bees movements as they came and went from their hive. The scientists fed some bees sugar water with a low dose of a neonicotinoid. The study found that these bees were about twice as likely not to return as other bees. Dave Goulson at the University of Stirling in Britain worked on another study published in Science. He says the pesticides could help explain why bumblebee populations are also decreasing. Bayer CropScience makes neonicotinoid pesticides. The companys spokesman Jack Boyne disputed the findings. He also notes that researchers are studying other factors that could affect the bees population. These include parasites, diseases and stress caused by transporting beehives to farms. Some European countries have banned the pesticides. And there are growing calls to ban them in the United States as well. 1．The underlined word“shrinking”in Paragr