Questions 46 to 50 are based on the following passage.
California has been facing a drought for many years now, with certain areas even having to pump freshwater hundreds of miles to their distribution system. The problem is growing as the population of the state continues to expand. 46.New research has found deep water reserves under the state which could help solve their drought crisis. Previous drilling of wells could only reach depths of 1,000 feet, 47.but due to new pumping practices, water deeper than this can now be extracted (抽取). The team at Stanford investigated the aquifers(地下蓄水层)below this depth and found that reserves may be triple what was previously thought.
It is profitable to drill to depths more than 1,000 feet for oil and gas extraction, but only recently in California has it become profitable to pump water from this depth. The aquifers range from 1,000 to 3,000 feet below the ground, which means that pumping will be expensive and there are other concerns. 48.The biggest concern of pumping out water from this deep in the gradual settling down of the land surface. As the water is pumped out, the vacant space left is compacted by the weight of the earth above.
Even though pumping from these depths is expensive, it is still cheaper than desalinating(脱盐)the ocean water in the largely coastal state. Some desalination plants exist where feasible, but they are costly to run and can need constant repairs.49. Wells are much more reliable sources of freshwater, and California is hoping that these deep wells may be the answer to their severe water shortage.One problem with these sources is that the deep water also has a higher level of salt than shallower aquifers. 50.This means that some wells may even need to undergo desalination after extraction, thus increasing the cost. Research from the exhaustive study of groundwater from over 950 drilling logs has just been published. New estimates of the water reserves now go up to 2,700 billion cubic meters of freshwater.
46.How could California’s drought crisis be solved according to some researchers?
A) By building more reserves of groundwater.
B) By drawing water from the depths of the earth.
C) By developing more advanced drilling devices.
D) By upgrading its water distribution system.
利用题干关键词定位文章第一段，通过关键词found 确定重点内容为deep water reserves under the state which could help solve their drought crisis.以及后文的数据实验作为例证，可知危机可通过开采地下水解决。于是B选项同义替换。A选项偷换概念，并没有建立更多的动作。C选项无中生有原文并未提及先进的钻井技术。D选项无中生有，并未提及水利调配体系。
47.What can be inferred about extracting water from deep aquifers?
A) It was deemed vital to solving the water problem.
B) It was not considered worth the expense.
C) It may not provide quality freshwater.
D) It is bound to gain support from the local people.
根据题干定位到第一段划线部分but due to new pumping practices, water deeper than this can now be extracted (抽取). The team at Stanford investigated the aquifers(地下蓄水层)below this depth and found that reserves may be triple what was previously thought.解题关键词依旧为found，因为此题目为推理题，于是答案应当为原文的间接表达。原文中说地下水的储备量超过了预期的三倍。于是可以判断之前对于地下水量的态度较为保守，认为不应该进行开采，于是选择B选项。A选项与原文意见相反。C、D均为无中生有。
48. What is mentioned as a consequence of extracting water from deep underground?
A) The sinking of land surface. C) The damage to aquifers.
B) The harm to the ecosystem. D) The change of the climate.
此题目按照顺序原则回文定位，可发现题干论述过于抽象，课利用选项短语回文定位The biggest concern of pumping out water from this deep in the gradual settling down of the land surface. As the water is pumped out, the vacant space left is compacted by the weight of the earth above.其中只有A选项符合文意，为同义替换+原词选项。B、C、D均未提及。
49. What does the author say about deep wells?
A) They run without any need for repairs.
B) They are entirely free from pollutants.
C) They are the ultimate solution to droughts.
D) They provide a steady supply of freshwater.
利用顺序原则，将题干定位到文中划线位置Wells are much more reliable sources of freshwater, and California is hoping that these deep wells may be the answer to their severe water shortage 可知D选项为原词+同义替换。A、B、均未提及。C选项偷换概念，将answer替换成了ultimate solution。
50. What may happen when deep aquifers are used as water sources?
A) People’s health may improve with cleaner water.
B) People’s water bills may be lowered considerably.
C) The cost may go up due to desalination.
D) They may be exhausted sooner or later.
利用文章剩下内容，讲关键词锁定在problem、means、thus因此可将解题句确定在This means that some wells may even need to undergo desalination after extraction, thus increasing the cost. C选项为原文。A、B、D无中生有。
Questions 51 to 55 are based on the following passage.
The AlphaGo program’s victory is an example of how smart computers have become.
But can artificial intelligence (AI) machines act ethically, meaning can they be honest and fair?
One example of AI is driverless cars. They are already on California roads, so it is not too soon to ask whether we can program a machine to act ethically. As driverless cars improve, they will save lives. They will make fewer mistakes than human drivers do. Sometimes, however, they will face a choice between lives. Should the cars be programmed to avoid hitting a child running across the road, even if that will put their passengers at risk? What about making a sudden turn to avoid a dog? What if the only risk is damage to the car itself, not to the passengers?
Perhaps there will be lessons to learn from driverless cars, but they are not super-intelligent beings. Teaching ethics to a machine even more intelligent than we are will be the bigger challenge.
About the same time as AlphaGo’s triumph, Microsoft’s ‘chatbot’ took a bad turn. The software, named Taylor, was designed to answer messages from people aged 18-24. Taylor was supposed to be able to learn from the messages she received. She was designed to slowly improve her ability to handle conversations, but some people were teaching Taylor racist ideas. When she started saying nice things about Hitler, Microsoft turned her off and deleted her ugliest messages.
AlphaGo’s victory and Taylor’s defeat happened at about the same time. This should be a warning to us. It is one thing to use AI within a game with clear rules and clear goals. It is something very different to use AI in the real world. The unpredictability of the real world may bring to the surface a troubling software problem.
Eric Schmidt is one of the bosses of Google, which own AlphoGo. He thinks AI will be positive for humans. He said people will be the winner, whatever the outcome. Advances in AI will make human beings smarter, more able and “just better human beings.”
51.What does the author want to show with the example of AlphaGo’s victory?
A)Computers will prevail over human beings.
B)Computers have unmatched potential.
C)Computers are man’s potential rivals.
D)Computers can become highly intelligent.
解析：用题干the example of AlphaGo’s victory定位至第一段，通过The AlphaGo program’s victory is an example of how smart computers have become. Alphago的成功是电脑已经变得很聪明的一个例子。因此D项电脑可以变得高智能符合题意。A B C在此处文意没有体现。
52.What does the author mean by AI machines acting ethically?
A)They are capable of predicting possible risks.
B)They weigh the gains and losses before reaching a decision.
C)They make sensible decisions when facing moral dilemmas.
D)They sacrifice everything to save human lives.
解析：通过题干acting ethically定位至第三段，答案在转折后：人工智能在无人驾驶方面，可以比司机犯更少的错，“Sometimes, however, they will face a choice between lives.”但是有时会面临生命间的选择。A的predicting预测无中生有，D sacrifice everything牺牲一切语气太过绝对，无中生有，B在做出选择前衡量得失与C面临道德困境时做出理智选择，C选项更贴合原文。
53.What is said to be the bigger challenge facing humans in the AI age?
A)How to make super-intelligent AI machines share human feelings.
B)How to ensure that super-intelligent AI machines act ethically.
C)How to prevent AI machines doing harm to humans.
D)How to avoid being over-dependent on AI machines.
解析：通过题干the bigger challenge定位至第三段“Teaching ethics to a machine even more intelligent than we are will be the bigger challenge”，因此选B
54.What do we learn about Microsoft’s ‘chatbot’ Taylor?
A)She could not distinguish good from bad.
B)She could turn herself off when necessary.
C)She was not made to handle novel situations.
D)She was good at performing routine tasks.
解析：通过题干定位至第五段，由“but some people were teaching Taylor racist ideas. When she started saying nice things about Hitler, Microsoft turned her off and deleted her ugliest messages.”可知，A选项Taylor无法区分好和坏正确。B选项是它可以自己关闭，而原文是微软关掉它，C选项与原文“She was designed to slowly improve her ability to handle conversations”意思正相反，D选项无中生有。
55. What does Eric Schmidt think of artificial intelligence?
A) It will be far superior to human beings.
B) It will keep improving as time goes by.
C) It will prove to be an asset to human beings.
D) It will be here to stay whatever the outcome.
解析：通过题干定位至最后一段，A B D无中生有，原文Eric Schmidt认为人工智能对人类发展有利，由原文“He thinks AI will be positive for humans. He said people will be the winner, whatever the outcome…”可知C选项正确。
2018年12月英语四级真题仔细阅读 Part C：仔细阅读 Passage One 【试题】 46 How could California& 39;s drought
2018年12月英语四级真题长篇阅读 Part B：长篇阅读 【试题】 Food-as Medicine Movement is witnessing progress [A
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2018年12月英语四级仔细阅读真题答案解析 Section C Passage One Questions 46 to 50 are based on the following
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