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一、题文

Escaping predators (食肉动物), digestion and other animal activities—including those of humans—require oxygen. But that essential ingredient is no longer so easy for marine life to obtain, several new studies reveal.In the past decade ocean oxygen levels have taken a dive—an alarming trend that is linked to climate change, says Andreas Oschlies, an oceanographer at the Helmholtz Center for Ocean Research in Germany, whose team tracks ocean oxygen levels worldwide. “We were surprised by the intensity of the changes we saw, how rapidly oxygen is going down in the ocean and how large the effects on marine ecosystems are,” he says. It is no surprise to scientists that warming oceans are losing oxygen, but the scale of the drop calls for urgent attention. Oxygen levels in some tropical (热带的) regions have dropped by an astonishing 40 percent in the last 50 years, some recent studies reveal. Levels have dropped less significantly elsewhere, with an average loss of 2 percent globally.A warming ocean loses oxygen for two reasons: First, the warmer a liquid becomes, the less gas it can hold. That is why carbonated drinks go flat faster when left in the sun. Second, as polar sea ice melts, it forms a layer of water above colder, more salty sea waters. This process creates a sort of lid that can keep currents from mixing surface water down to deeper depths. And because all oxygen enters the surface, less mixing means less of it at depth.Ocean animals large and small, however, respond to even slight changes in oxygen by seeking refuge in higher oxygen zones or by adjusting behavior, Oschlies and others in his field have found. These adjustments can expose animals to new predators or force them into food-scarce regions. Climate change already poses serious problems for marine life, such as ocean acidification, but deoxygenation is the most pressing issue facing sea animals today, Oschlies says. After all, he says, “they all have to breathe.”Aside from food web problems, animals face various other physiological challenges as their bodies adjust to lower oxygen levels. Chinese shrimp (虾) move their tails less vigorously to preserve energy in lower oxygen environments. Some creatures, such as jellyfishes, are more tolerant of low oxygen than others are. But all animals will feel the impact of deoxygenation because they all have evolved their oxygen capacity for a reason, says Oschlies. “Any drop in oxygen is going to damage survivability and performance,” he says.【小题1】According to the first two paragraphs, what worries scientists the most?A．The worsening deoxygenation in the warming ocean.B．The survival of predators and various marine animals.C．The alarmingly changeable oxygen levels in the ocean.D．The lack of attention to the warming of tropical oceans.【小题2】Which of the following is a reason for the oxygen loss in the ocean?A．Polar ice melting consumes much oxygen in the ocean.B．Global warming reduces the amount of oxygen in the air.C．The surface polar ice water prevents oxygen going down.D．Salty water holds less gas in the increasingly warmer ocean.【小题3】What can be inferred from the passage?A．Ocean deoxygenation changes some animals’ natural territories.B．Ocean acidification is more serious a problem than deoxygenation.C．Not all ocean animals are bothered by the decreasing oxygen levels.D．Some animals reduce their movements in order to absorb more oxygen.【小题4】Which of the following is the best title of the passage?A．The Oxygen Levels of Marine LifeB．Ocean Warming Affects Food WebC．The Survivability of Ocean AnimalsD．The Ocean Is Running Out of Breath

二、解答

【文章大意】对于地球上的生物来说，氧气是必不可缺少的物质。但是，一些新的研究表明，对于海洋生物而言，这种基本成分已不再那么容易获得。对于科学家来说，变暖的海洋正在失去氧气就不足为奇，但是下降的幅度需要紧急关注。最近的一些研究表明，在过去的50年中，某些热带地区的氧气含量下降了惊人的40％。其他地方的水温下降幅度不大，全球平均下降2％。1【答案】A【解析】题干意思为 根据前两段，科学家最担心的是什么？根据第一段But that essential ingredient is no longer so easy for marine life to obtain,（对于海洋生物而言，这种基本成分已不再那么容易获得） 和第二段It is no surprise to scientists that warming oceans are losing oxygen, but the scale of the drop calls for urgent attention. Oxygen levels in sometropical regions have dropped by an astonishing 40 percent in the last 50 years,（对于科学家来说，变暖的海洋正在失去氧气就不足为奇，但是下降的幅度需要紧急关注。最近的一些研究表明，在过去的50年中，某些热带地区的氧气含量下降了惊人的40％。）结合选项 A.在变暖的海洋中，越来越严重的脱氧。B．捕食者和各种海洋动物的生存。C．海洋中的氧气含量惊人地变化。D．缺乏对热带海洋变暖的关注。可知此题选A。2【答案】C【解析】题干意思为 以下哪些是造成海洋氧气流失的原因？根据第三段as polar sea ice melts, it forms a layer of water above colder, more salty sea waters. This process creates a sort of lid that can keep currents from mixing surface water down to deeper depths. And because all oxygen enters the surface, less mixing means less of it at depth.（，随着极地海冰融化，它在较冷，更咸的海水上方形成了一层水。这个过程产生了一种盖子，可以防止电流将表面水混合到更深的深度。而且由于所有氧气都进入表面，因此较少的混合意味着在深度处较少的氧气。） 结合选项A.极地冰融化在海洋中消耗大量氧气。B.全球变暖减少了空气中的氧气量。C．极地表面的冰水防止氧气下落。D．咸水在日益温暖的海洋中所含的气体较少。可知此题选C。3【答案】A【解析】题干意思为 从这段文字可以推断出什么？根据第四段Ocean animals large and small, however, respond to even slight changes in oxygen by seeking refuge in higher oxygen zones or by adjusting behavior（无论大小，海洋动物对氧气的微小变化都会通过在较高氧气区域寻求庇护或通过调整行为来做出响应。）和Climate change already poses serious problems for marine life, such as ocean acidification, but deoxygenation is the most pressing issue facing sea animals today,（气候变化已经给海洋生物带来了严重的问题，例如海洋酸化，但是脱氧是当今海洋动物面临的最紧迫的问题。）they all have to breathe.（所有人都必须呼吸。）和最后一段But all animals will feel the impact of deoxygenation because they all have evolved their oxygen capacity for a reason（但是所有动物都会感受到脱氧的影响，因为它们都有一定的理由发展了其氧气容量。） 结合选项A.海洋脱氧改变了某些动物的自然领土。B．海洋酸化比脱氧更严重。C．并不是所有的海洋动物都被氧气水平的降低所困扰。D．有些动物为了吸收更多的氧气而减少运动。可知此题选A。4【答案】D【解析】题干意思为 以下哪项是该段落的最佳标题？根据文章大意可知整篇文章都在论述海洋缺氧这个事实。文章最后一段更列举了一些海洋生物因为缺氧的变化。 结合选项A海洋生物的氧气水平B．海洋变暖影响食物网。C．海洋动物的生存能力。D．海洋快要喘不过气了。可知此题选D。

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