题目

Half of the world’s coral reefs have died in the last 30 years. Now scientists are racing to ensure that the rest will survive. “The threat to coral reefs isn’t something that’s going to happen 100 years from now. We’re losing them right now,” Julia Baum told the Associated Press. She is a marine biologist at the University of Victoria, in British Columbia, Canada. “We’re losing them really quickly, much more quickly than I think any of us ever could have imagined.” Even if global warming were in stop right now, scientists predict that more than 90% of corals will die by 2050. If no major steps are taken to address the issue, the reefs may be headed for total extinction. The planet’s health depends on the survival of coral reefs. They are often described as underwater rainforests, because they are ecosystems that provide habitats for one in four of all marine species. In addition, the reefs serve as barriers that protect coastlines from the full force of powerful storms. Corals are used in medical research for cures to diseases. They are key to local economies, as well, since the reefs attract tourists, the fishing industry, and other businesses, bringing in billions of dollars of revenue ( 收入 ). “To lose coral reefs is to fundamentally damage the health of the human race,” Ruth Gates, director of the Hawaii Institute of Marine Biology, said. Corals are animals that lack a backbone. They live mostly in tropical waters. The corals release a substance called calcium carbonate ( 碳酸钙 ), which forms protective skeletons around them. The skeletons grow and take on vivid colors. This is the result of the corals’ mutually beneficial relationship with algae ( 藻类 ) that live in their tissues ( 组织 ) and give them energy. But corals are particularly sensitive to changes in temperature. A rise of just 1 to 2 degrees Celsius can force the corals to drive out the algae. Then the corals’ skeletons turn white in a process called “bleaching”. Corals can survive in these higher temperatures only for a few months. 1 ． What can we know about the world’s coral reefs? A ． The number of the world’s coral reefs is on the decrease. B ． 45% of the world’s coral reefs have died in the last 30 years. C ． Global warming has no influence on the world’s coral reefs. D ． Scientists have taken major steps to address the issue of world’s coral reefs. 2 ． Paragraph 4 is mainly about _____. A ． economic value of coral reefs B ． the challenges faced by coral reefs C ． the medical functions of coral reefs D ． the importance of coral reefs. 3 ． What makes corals take on different colors? A ． Changes in temperature. B ． Ocean waters. C ． Algae living inside corals. D ． Protective skeletons. 4 ． The corals’ skeletons turn white when _____. A ． there is not enough oxygen. B ． there are no algae in the corals’ skeletons. C ． water pollution is worsening. D ． the ocean temperature is too low. 答案： 1 ． A 2 ． D 3 ． D 4 ． B 【分析】 这是一篇说明文。文章主要讲述了珊瑚礁受到全球变暖的威胁，以及人们为使其适应环境做出的努力。 1 ． 细节理解题。根据文章第一段 “Half of the world’s coral reefs have died in the last 30 years.( 在过去的 30 年里，世界上一半的珊瑚礁已经死亡 )” 和文章第三段 “Even if global warming were in stop right now, scientists predict that more than 90% of corals will die by 2050.( 即使全球变暖现在停止了，科学家预测，到 2050 年，超过 90% 的珊瑚将死亡 )” 可知，世界上珊瑚礁的数量正在减少。故选 A 。 2 ． 主旨大意题。根据文章第四段内容 “The planet’s health depends on the survival of coral reefs…bringing in billions of dollars of revenue.( 地球的健康依赖于珊瑚礁的生存。它们通常被称为水下雨林，因为它们是为四分之一的海洋物种提供栖息地的生态系统。此外，珊瑚礁还可以作为屏障，保护海岸线免受强烈风暴的冲击。珊瑚被用于医学研究以治疗疾病。它们也是当地经济的关键，因为珊瑚礁吸引了游客、捕鱼业和其他行业，带来了数十亿美元的收入 )” 可知，第四段主要讲述了珊瑚礁的重要性。故选 D 。 3 ． 细节理解题。根据文章第六段 “The corals release a substance called calcium carbonate( 碳酸钙 ), which forms protective skeletons around them. The skeletons grow and take on vivid colors.( 珊瑚会释放一种叫做碳酸钙的物质，在它们周围形成保护性骨架。骨骼生长并呈现出鲜艳的颜色 )” 可知，保护性骨骼使珊瑚呈现出不同的颜色。故选 D 。 4 ． 细节理解题。根据文章最后一段 “A rise of just 1 to 2 degrees Celsius can force the corals to drive out the algae. Then the corals’ skeletons turn white in a process called “bleaching”.( 仅仅升高 1 到 2 摄氏度就会迫使珊瑚驱赶藻类。然后珊瑚的骨骼会在一个叫做 “ 漂白 ” 的过程中变白 )” 可知，当珊瑚的骨骼中没有藻类时，珊瑚的骨骼就会变成白色。故选 B 。

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