1. distinguish vi. 区分，辦别，分清 vt. 使有别于；辨别出；使表现突出
例句：This is how children distinguish between good and evil.（这就是孩子分辨好人和坏人的方法）
2. intellectualad adj. 智力的，脑力的；有才智的 n. 知识分子
例句：Gary was born with some intellectual disabilities.(盖瑞生来就有智力残疾。)
3. mutter v. 嘀咕；嘟囔；低声说
例句：She muttered her complaints to herself.（她喃喃自语地抱怨。）
4. quell v. 平息；镇压；消除（恐惧等）
例句：The general tried to quell the rumors spreading in the army.（将军试图平息在军队中传播的谣言。）
5. ulcer n. 溃疡
例句：Poor eating habits can aggravate an ulcer.（不良的饮食习惯会使溃疡恶化。）
6. eccentric adj. 古怪的；反常的 n. 古怪的人
例句：His eccentric behavior made him stand out in the crowd.（他古怪的行为使他在人群中很突出。）
7. ignite v. 点燃；引发；激起
例句：The fuel is easy to ignite in high temperatures.（这种燃料在高温下很容易点燃。）
8. pact n. 协定；条约；契约
例句：The pact was a crucial step towards peace.（这个协定是迈向和平的关键一步。）
9. nudge v.轻推；推动；敦促 n. 轻推
例句：A little nudge from his friend made him change his mind.（他朋友轻轻的推动使他 change his mind。）
10.institution n. 机构；收容机构；习俗，制度
例句：Banks, on the other hand, are financial institutions.(另一方面，银行是金融机构。)
Questions 1 to 5 are based on the following passage.
Scientists have created by accident an enzyme( 酶 )that breaks down plastic drinks .
bottles.The breakthrough could help solve the global plastic pollution crisis by enabling for the first time the full recycling of bottles.
The new research was spurred by the discovery in 2016 of the first bacterium that had naturally evolved to eat plastic at a waste dump in Japan.Scientists have now revealed the detailed structure of the crucial enzyme produced by the bug.
An international team then adjusted the enzyme to see how it had evolved,but tests showed they had accidentally made the molecule even better at breaking down the plastic used for drinks bottles.“What actually turned out was we improved the enzyme,which was a bit of a shock,”said head researcher Prof.McGeehan,at the University of Portsmouth, UK.
Currently,the enzyme takes a few days to start breaking down the plastic,far faster than the centuries it takes in the oceans,but the researchers are optimistic this can be speeded up even further and become a viable large-scale process.
“What we are hoping to do is use this enzyme to turn this plastic back into its original components,so we can literally recycle it back to plastic,”said McGeehan.“It means we won't need to dig up any more oil and,fundamentally,it should reduce the amount of plastic in the environment.”
About 1 million plastic bottles are sold each minute around the globe and,with just 14%recycled,many end up in the oceans where they have polluted even the remotest parts, harming marine life and potentially people who eat sea food.“Plastic is incredibly resistant to degradation,”said McGeehan.“It is one of these wonder materials that has been made a little bit too well.”
Currently those bottles that are recycled can only be turned into opaque fibres for clothing or carpets,while the new enzyme indicates a way to recycle old clear plastic bottles back into new clear plastic bottle.
“You are always up against the fact oil is cheap,so plastic is cheap,”said McGeehan. “It is so easy for manufacturers to generate more of that stuff,rather than even try to recycle,but I believe there is a public interest here:perception is changing so much that companies are starting to look at how they can properly recycle these bottles.”
Prof.Adisa Azapagic,at the University of Manchester in the UK,agreed the enzyme could be useful but added:“A full life-cycle assessment would be needed to ensure that the technology does not solve one environmental problem—waste—at the expense of others, including additional greenhouse gas emissions.”
1.What do we learn from the passage about an enzyme scientists have created?
A.It was identified during a lab experiment accident.
B.It may make full recycling of plastic bottles a reality.
C.It was a breakthrough made with persistent efforts.
D.It may initiate a radical reform in plastic industry.
2.What does the passage say about the bug that produces the important enzyme?
A.It has a natural ability to consume plastics.
B.It is a bacterium that reproduces at a high rate.
C.It is essential to the recycling of plastic bottles.
D.It has a chemical structure unknown to scientists.
3.By adjusting the enzyme produced by the bug,the scientists
A.made it more effective by chance
B.discovered an extraordinary chemical .
C.altered its basic molecular composition
D.found its evolutionary process sped up
4.What does Prof.McGeehan say about the recycling of plastic bottles?
A.Manufacturers are implementing it on an increasingly larger scale.
B.It generates huge business opportunities for plastic manufacturers.
C.It has aroused persistent interest among the general public.
D.Manufacturers are beginning to explore ways of doing it.
5.What is Prof.AdisaAzapagic's advice concer-ning the application of the enzyme?
A.Developing technologies to address greenhouse gas emissions. B.Considering the extra cost involved in producing the enzyme. C.Assessing its possible negative impact on the environment.
D.Studying the full life cycle of the enzyme as the first step.
一、云贵高原(the Yunnan-Guizhou Plateau)大部分位于云南、贵州省境内，总面积约50万平 方公里，平均海拔2000-4000米，是中国第四大高原。
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二、云贵高原西高东低，河流众多，形成 了许多又深又陡的峡谷(canyon)。峡谷中许多地方土壤肥沃，非常有利于多种农作物生长。
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三、云贵高原独特的自然环境造就了生物和文化的多样性。它是中国森林和矿产资源类型十 分丰富的地区，也是古人类起源的重要地区。
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四、云贵高原是中国少数民族数量最多的地区，各 民族都保留了自己丰富多彩的文化传统。
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DAACD阅读理解
1.【D】由题干中的“No screens under 2”rule定位到第一、二段。(D)【精析】事实细节题。文章首段第一句指出，大多数父母认为在孩子未满2周岁之前，应该限制孩子看屏幕。第二段第一句指出，但从今天起，这条规则就不适用了。由此可知，“未满2周岁之前，限制孩子看屏幕”这条规则现在已经不提倡了，故答案为(D)。
【避错】首段第一句指出大多数父母认为在孩子未满2周岁之前，应该限制孩子看屏幕，即他们赞成这条规则，而不是抵制这条规则，(A)项表述与此矛盾，故排除；本文并未提及相关证据说明这条规则有助于儿童的健康成长，故排除 (B)项；根据首段第一句可知，大多数父母赞成这条规则，而非使父母对儿童的教育感到困惑，故排除(C)项。
2.【A】由题干中的 new AAP guidelines 和 advocate 定位到第四段和七段。(A)【精析】推理判断题。文章第四段第一句指出，这项新的指导方针，特别是针对非常年幼的儿童的部分，将重点从屏幕上的内容转向房间里的其他人。文章第七段第一句指出，只有当父母和孩子一起观看视频，并且对孩子重复视频中的内容，或者提示孩子注意屏幕上的内容时，孩子才能从教育媒体中学到新单词。由此可知，新指南提倡在看屏幕期间，年幼的孩子应该有父母陪伴，故答案为(A)。
3.【A】由题干中的 families 和 livevideochat定位到第五段。【精析】推理判断题。文章第五段第二句指出，调查显示，美国家庭已经普遍认为“实时视频聊天没事”,或者至少他们认为云端看望祖父母或其他亲戚的好处要大于让婴儿接触笔记本电脑或智能手机的潜在危害。由此可知，调查表明，家庭认为实时视频聊天不应被视为屏幕时间，故答案为(A)。
【避错】定位句并未提及美国家庭认为和家人实时视频聊天有助于婴儿发展他们的语言技能，(B)项表述与原文不符，故排除；根据定位句可知，“实时视频聊天没事”,或者至少他们认为云端看望祖父母或其他亲戚的好处，要大于让婴儿接触笔记本电脑或智能手机的潜在危害。这里是指与家人实时聊天的好处大于孩子接触电脑或者手机，文章没有把实时视频聊天和在电脑上打游戏的危害做比较，故排除(C)项；根据定位句可知，美国家庭认为实时视频聊天不算屏幕时间，但该调查并没有指出美国家庭认为实时视频聊天可以替代视频观看，(D)项为过度推理，故排除。
4.【C】由题干中的kid ssoloviewing education alvideos定位到第八段第一句。(C)【精析】事实细节题。文章第八段第一句指出，另一方面，许多研究实际明，孩子语言技能较差与其早期单独观看“教育”视频相关。由此可知，孩子自己看视频，会阻碍他们语言技能的发展，故答案为(C)。
【避错】定位句指出，孩子语言技能较差与其早期单独观看“教育”视频相关，即孩子自己看视频会影响语言发展，而非引起了他们对语言学习的兴趣，故排除 (A)项；第七段最后一句指出，把视频或应用程序当作一本图画书，这种方法最佳，但并没有把自己单独看视频和读图画书相比较，故排除 (B)项；定位句指出孩子自己单独看视频会影响语言发展，而非会帮助他们获得独立的学习技能，故排除(D)项。
5.【D】由题干中的ages 2 to 5定位到最后一段第一句。(D)【精析】推理判断题。文章最后一段第一句指出，对于2至5岁的学龄前儿童，有更多证据表明他 们有能力将知识从屏幕转移到现实世界，包括早期识字和数学。由此可知，2至5岁的学龄前儿童 可以将屏幕上学到的内容与现实生活情境联系起 来，故答案为(D)。
【避错】最后一段第一句指出，2至5岁的学龄前儿童可以将屏幕上学到的内容与现实生活情境联 系起来，而非可以很好地理解他们在屏幕上看到 的内容，故排除(A)项；最后一段最后一句指出，正 如与更年幼的孩子一起观看一样，该指南希望照 顾者也能参与到屏幕时间中，与孩子共同观看，而 非孩子可以在没有父母指导的情况下自学，故排 除(B)项；文章最后一段第一句指出，对于2至5岁的学龄前儿童，有更多证据表明他们有能力将知 识从屏幕转移到现实世界，包括早期识字和数学，文中提到的是数学，而不是digital literacy“数字 素养”,故排除(C)项。
重点翻译
一、The Loess Plateau is the third largest plateau in China,with an area of about 600,000 square kilometers and an average altitude of 1,000-2,000 meters.Most of the plateau is covered with 50-80 meters thick loess,which has the most concentrated distribution and the greatest thickness in the world.
二、This is a miracle created by nature, and it is unique in the world.The Loess Plateau is one of the birthplaces of the Chinese nation.
三、As early as 5,500 years ago,people have already started farming on the Loess Plateau. With the continuous development of farming,the population of the Loess Plateau continued to increase,and it became the political and economic center of China during the Qin and Han Dynastides.
四、Nowadays,with the implementation of strategy for large- scale development of western China, the economy of the Loess Plateau region has been developing rapidly.
预祝所有参加四六级考试的同学们顺利通过！
编辑 | 阿布都沙拉木·艾麦提
责编 | 郑馨怡 包芳臣
审校 | 舒尔娜·吾其尔 张如
