Question

    New research suggests that dogs might be able to help save diseased citrus trees. 

A group of scientists trained dogs to use their sense of smell to detect a crop disease called citrus-greening. The disease has affected orange, lemon and grapefruit trees in the American states of Florida, California and Texas.

The dogs can detect the disease weeks to years before it appears on tree leaves and roots, the researchers report. A study on their findings was published recently in the Proceedings of the National Academy of Sciences. The report says using dogs is also faster, less costly and more exact than having people collect hundreds of leaves for lab analysis.

Timothy Gottwald is a researcher with the U. S. Department of Agriculture and a co-writer of the study. He told The Associated Press,” This technology is thousands of years old-the dog's nose. We've just trained dogs to hunt new prey. ”

Citrus-greening is caused by a bacteria (细菌) that is spread by a tiny insect that feeds on the leaves and stems of citrus trees. Once a tree is infected(感染), there is no cure. The disease has also hurt citrus crops in Central and South America and Asia. In one experiment involving grapefruit trees in Texas, trained dogs were correct 95 percent of the time in telling the difference between newly infected trees and healthy ones. ”The earlier you detect a disease, the better chance you have at stopping an epidemic(流行病）by removing infected trees, ”Gottwald said.

Matteo Garbelotto studies plants at the University of California, Berkeley. He says the new research shows that dogs can detect an infection well before current methods. Garbelotto has been involved in similar research but had no part in the new study.

Laura Sims is a plant scientist with Louisiana Tech University. She praised the steps taken to find out if the dogs were detecting the bacteria itself or a plant's reaction to an infection. To do that, the researchers infected different kinds of unrelated plants with the bacteria in a laboratory. The dogs were still able to pick out the infected plants.

Gottwald said, “You've seen dogs working in airports, detecting drugs and explosives. Maybe soon you will see them working on more farms. ”

1.According to the research, trained dogs can

A.help infected trees recover from diseases

B.recognize a crop disease in its early stage

C.cause fruit trees to grow faster than usual

D.reduce the cost of planting some fruit trees

2.What does the underlined part “new prey” in Paragraph 4 refer to?

A.Infected plants. B.Fruit trees. C.Tiny insects. D.Favourite foods.

3.Why did the researchers do experiments on unrelated plants?

A.To further prove the findings. B.To explore the plant diseases.

C.To present different opinions. D.To discover a plant's reactions.

4.How does Gottwald feel about the future use of this new method?

A.Doubtful. B.Confident. C.Uninterested. D.Curious.

Answer

1.B

2.A

3.A

4.B

【解析】

本文是一篇说明文。本文讲述了狗狗能嗅出影响作物，尤其是柑橘树的病害。

1.

细节理解题。根据第三段The dogs can detect the disease weeks to years before it appears on tree leaves and roots, the researchers report.可知，研究人员报告说，狗能在树叶和树根上出现疾病前数周到数年发现它。由此可知，训练有素的狗能在作物疾病的早期阶段识别出它。故选B。

2.

词义猜测题。根据第五段 trained dogs were correct 95 percent of the time in telling the difference between newly infected trees and healthy ones. 可知，训练有素的狗在95%的时间里能正确地分辨出新感染的树木和健康的树木之间的区别。再结合划线词组所在句We've just trained dogs to hunt new prey. 可知，人们训练狗的目的是寻找收到感染的植物，所以划线短语“new prey” 指的是感染的植物。故选A。

3.

推理判断题。根据倒数第二段She praised the steps taken to find out if the dogs were detecting the bacteria itself or a plant's reaction to an infection. To do that, the researchers infected different kinds of unrelated plants with the bacteria in a laboratory. 可知，为查明这些狗是在检测细菌本身还是植物对感染的反应而采取的措施。为此，研究人员在实验室用这种细菌感染了不同种类的无关植物。由此可推知，研究人员在不相关的植物上做实验以进一步证明这一发现——训练有素的狗能在作物疾病的早期阶段识别出它。故选A。

4.

推理判断题。根据最后一段You've seen dogs working in airports, detecting drugs and explosives. Maybe soon you will see them working on more farms. 可知，Gottwald说，你见过狗在机场工作，检测毒品和爆炸物。也许很快你就会看到他们在更多的农场工作。由此推知，Gottwald对于用狗来发现农作物病害信心满满。故选B。