Question

    A group of scientists trained dogs to detect(发现)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. 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 in the study. He said, “This technology is thousands of years old — the dog's nose. We^’ve just trained dogs to hunt new prey：the bacteria that cause a very damaging crop disease.^”

Citrus greening is caused by a kind of bacteria that are 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 the disease, the better chance you have at stopping healthy trees being infected by removing infected ones,” Gottwald said.

Professor Matteo Garbelotto says the new research shows that dogs can detect an infection well before present methods. He has been involved in similar research but had no part in the new study.

Laura Sims is a plant scientist. 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.What does the text say about citrus greening?

A.It mainly damages tree branches.

B.It' s impossible to detect at an early stage.

C.Dogs can better detect it than humans.

D.Humans have to analyze tree roots to detect it.

2.How does a dog detect citrus greening?

A.By tasting. B.By touching.

C.By observing. D.By Sniffing.

3.Early detection of citrus greening enables farmers to ______.

A.help infected trees to recover B.keep it from spreading further

C.improve the quality of fruit. D.better protect infected trees

4.Which of the following statements reflects Gottwald's opinion?

A.Dogs will take the place of humans to conduct risky jobs.

B.Trained dogs make no mistakes in citrus greening detection.

C.Dogs use plants' reaction to an infection to help with their detection.

D.Using dogs for citrus greening detection will be more widespread.

Answer

1.C

2.D

3.B

4.D

【解析】

本文是说明文。柑橘黄龙病已经影响了美国很多州的柑橘类树种。科学家训练狗用鼻子去嗅这种病的病菌。

1.细节理解题。根据第一段中“The dogs can detect the disease weeks to years before it appears on tree leaves and roots, the researchers report. Using dogs is also faster, less costly and more exact than having people collect hundreds of leaves for lab analysis.”可知, 狗能在树叶和树根上出现疾病前数周甚至数年发现它。与让人收集数百片树叶进行实验室分析相比，用狗发现病菌会更快、更便宜、更精确。因此狗比人能更快更准确地察觉到柑橘黄龙病。故选C项。

2.细节理解题。根据第二段中“‘This technology is thousands of years old — the dog's nose. We’ve just trained dogs to hunt new prey: the bacteria that cause a very damaging crop disease.’”可知， 根据研究员Timothy Gottwald所说，这项技术是通过训练狗用鼻子去寻找新的猎物，即那些会导致非常有害的农作物疾病的细菌，是让狗用鼻子去嗅柑橘黄龙病。故选D项。

3.推理判断题。根据第三段中““The earlier you detect the disease, the better chance you have at stopping healthy trees being infected by removing infected ones,” Gottwald said. （戈特瓦尔德说：“你越早发现这种疾病，就越有可能通过移除受感染的树木来阻止健康树木被感染。”）”可以推断，早期发现柑橘黄龙病可以预防它进一步传播。故选B项。

4.推理判断题。根据最后一段中“Gottwald said, "You've seen dogs working in airports, detecting drugs and explosives. Maybe soon you will see them working on more farms.（哥特瓦尔德说：“你在机场看到过警犬检测毒品和爆炸物。也许很快你就会看到他们在更多的农场干活。”）”可以推断，哥特瓦尔德认为将来用狗检测柑桔黄龙病将会更加普遍。故选D项。