【正文】 system to lightadjusting glasses. When a person wears the glasses outside during the day, the lenses（鏡片）darken and lighten depending on how sunny it is. Plants do the same thing, he said. But in plants the adjustment can take anywhere from 10 minutes to an hour. This makes it hard for plants to get the right amount of sunlight needed to create food. The new study sped up the process. By changing the plant39。s genes, the protective system turned on and off more quickly than normal. As a result, leaf growth on the plants scientists used in the study increased. Leaf growth in two plants increased by 20 percent, while leaf growth on a third plant increased by 14 percent. Scientists conducted the study on tobacco plants. But they think the genetic changes will produce the same results in corn and rice. （1）What will happen to the plants when scientists change plants39。 genes？ A.They will bee weaker and weaker.B.They will grow fast to produce more food.C.They will have more beautiful flowers.D.They will depend less on sunlight.（2）Why does the author mention lightadjusting glasses？ A.To warn people of the hot and bright sun.B.To explain the principle of plants39。 protective system.C.To help leaves of the plants absorb sunlight.D.To serve the science experiment smoothly.（3）In the future, the genetic changes will be used to. A.improve tobacco plants39。 qualityB.increase tobacco plants39。 leaves and rootsC.improve the flowers39。 living timeD.increase the production of corn and rice（4）Which of the following can be the theme of this text？ A.Hacking plants for more productionB.Leaf growing more quicklyC.Double production of tobacco plantsD.Photosynthesis and production【答案】 （1）B（2）B（3）D（4）A 【解析】【分析】本文是一篇說明文，科學家通過改變植物的基因，加快光合作用的速度，使植物葉子生長迅速，從而提高植物產(chǎn)量。 （1）考查細節(jié)理解。根據(jù)第一段中的“ scientists have found a way to hack a plant39。s genes in order to make it use sunlight more quickly. Someday, the results could increase the amount of food produced around the world. ”可知，科學家發(fā)現(xiàn)改變植物基因會使植物的光合作用速度加快，將來會增加全球植物的產(chǎn)量。故選B。 （2）考查推理判斷。根據(jù)第四段中的“ He pared a plant39。s protective system to lightadjusting glasses. When a person wears the glasses outside during the day, the lenses（鏡片）darken and lighten depending on how sunny it is. Plants do the same thing, he said. But in plants the adjustment can take anywhere from 10 minutes to an hour. ”可知，作者提到鏡片是為了說明植物的保護系統(tǒng)的工作原理與鏡片相同。故選B。 （3）考查細節(jié)理解。根據(jù)最后一段中的“ But they think the genetic changes will produce the same results in corn and rice. ”但是他們認為基因的改變將在玉米和水稻中產(chǎn)生相同的結(jié)果?？芍xD。 （4）考查主旨大意，根據(jù)文章內(nèi)容可知，科學家改變植物的基因，加快光合作用的速度，使植物葉子生長迅速，從而提高植物產(chǎn)量。故選A。 【點評】本題考點涉及細節(jié)理解，推理判斷和主旨大意三個題型的考查，是一篇科研類閱讀，要求考生在捕捉細節(jié)信息的基礎(chǔ)上，進一步根據(jù)上下文的邏輯關(guān)系，進行分析，推理，概括和歸納，從而選出正確答案。7．犇犇Choose the one that fits best according to the information given in the passage you have just read. Escaping predators (食肉動物), 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 (熱帶的) 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 bees, 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 foodscarce 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 (蝦) 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.（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.（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