2019年公共英语二级阅读理解练习题（13）

　　Around 200 million years ago, the earth was 18 degrees warmer than it is now. That might be a bit hot for humans, but it was just right for the giant dinosaurs that wandered about the earth during the Mesozoic (中生代的) era. A new study found that planteating dinosaurs may have contributed to the warming of the earth­by releasing significant amounts of methane (甲烷).

　　The study, published in science journal Current Biology, focused on sauropods, long­necked herbivores (食草动物) that munched (用力咀嚼) on the top of trees. They were the largest of the dinosaurs; food broke down in their stomachs for long periods of time. The researchers estimate that a sauropoda released 2,675 liters of methane per day—adding up to a large amount of the greenhouse gas being pumped from dinosaur's gut into the atmosphere.

　　Plant eaters naturally release methane as part of their digestive process. The larger the animal, the more methane it produces. Methane, a greenhouse gas, traps heat and remains in the atmosphere for approximately 9­15 years, which warms the atmosphere.

　　Today, some animals, such as cattle, goats and sheep, produce large amounts of methane as a by­product to their food digestion. Methane is also released from human—influenced sources such as landfill, agricultural activities, coal mining and other industrial practices—which all contribute to today's climate change, according to the Environmental Protection Agency.

　　The researchers estimate that earth's sauropods would have produced about 520 million tons of methane per year—similar to the total amount of methane produced today by natural and man­made sources. However, the researchers warn that their numbers are estimates based on multiple assumptions about the digestive systems and populations of dinosaurs.

　　The author of the study David Wilkinson says the emission of methane from dinosaurs would have been just one of the causes of warm climate during the Mesozoic era. Other causes include gases produced from volcanoes, swamps, shallow seas and so on. Still, Wilkinson says，“ The amount of methane from dinosaurs is large enough to have a measurable effect.”

　　小题1:Scientists think dinosaurs may have led to the global warming because ________.A.they ate everything they found

　　B.they usually had a good appetite

　　C.they released a lot of methane

　　D.there were too many dinosaurs on earth

　　小题2:What do we know about dinosaurs from Paragraph 2?A.Sauropods fed on plants.

　　B.Sauropods were of medium size.

　　C.Dinosaurs used to live on trees.

　　D.Dinosaurs digested food quickly.

　　小题3:Which of the following activities doesn't produce methane?A.Coal is dug out by machine.

　　B.Trees and flowers are planted.

　　C.Goats digest grass under the tree.

　　D.Food is being processed in the factory.

　　小题4:How does the author make his writing reliable?A.By listing some facts.

　　B.By making predictions.

　　C.By citing figures.

　　D.By using mind pictures.

　　小题5:David Wilkinson seems to believe that ________.A.methane had little effects on the earth

　　B.many other factors contributed to warm climate

　　C.other causes for warm climate were worth considering

　　D.dinosaurs were mainly to blame for global warming

　　参考答案及解析

　　小题1:C

　　小题2:A

　　小题3:B

　　小题4:C

　　小题5:B

　　文章大意：一项研究发现，中生代全球变暖很可能是因为恐龙释放出了大量的甲烷。

　　小题1:答案：C　细节理解题。根据第一段的最后一句可知，恐龙导致全球变暖是因为它们释放出了大量的甲烷。

　　小题2:答案：A　细节理解题。根据第二段的内容可知，蜥脚类恐龙是长脖子食草动物，体形硕大。故A项正确。

　　小题3:答案：B　细节理解题。根据第四段可知，动物消化食物时，会释放出甲烷。而且，在废物填埋、农业活动、煤矿开采以及其他工业生产过程中，都会产生甲烷。因此B项符合题意。

　　小题4:答案：C　推理判断题。作者在文中多次引用数字，以提高文章内容的可信度。

　　小题5:答案：B　推理判断题。根据最后一段的内容可知，David Wilkinson认为除了恐龙排放的甲烷之外，还有其他一些因素导致全球变暖。