To understand theancientMayan people who lived in the area that is today southern Mexico and Central America and theecologicaldifficulties they faced, one must firstconsidertheir environment, which we think of as "jungle" or "tropicalrainforest." This view is inaccurate, and thereasonproves to be important. Properly speaking,tropicalrainforests grow in high-rainfallequatorialareas thatremainwet orhumidall year round. But the Maya homeland lies more than sixteen hundred kilometers from theequator, at latitudes 17 to 22 degrees north, in ahabitattermed a "seasonaltropicalforest." That is, while there doestendto be a rainyseasonfrom May to October, there is also a dryseasonfrom JanuarythroughApril. If one focuses on the wet months, one calls the Maya homeland a "seasonaltropicalforest"; if one focuses on the dry months, one couldinsteaddescribeit as a "seasonaldesert."

From north to south in the YucatanPeninsula, where the Maya lived,rainfallranges from 18 to 100 inches (457 to 2,540 millimeters) per year, and the soils become thicker, so that the southernpeninsulawas agriculturally moreproductiveand supported denser populations. Butrainfallin the Maya homeland is unpredictablyvariablebetween years; some recent years have had three or four times more rain than other years. As a result, modern farmers attempting to grow corn in theancientMaya homelands have faced frequent crop failures, especially in the north. TheancientMaya werepresumablymore experienced and did better, butneverthelessthey too must have faced risks of crop failures from droughts and hurricanes.

Although southern Maya areas received morerainfallthan northern areas, problems of water were paradoxically moreseverein the wet south. While that made things hard forancientMaya living in the south, it has also made things hard for modern archaeologists who have difficulty understanding whyancientdroughts caused bigger problems in the wet south than in the dry north. The likely explanation is that an area ofundergroundfreshwater underlies the YucatanPeninsula, but surfaceelevationincreases from north to south, so that as one moves south the land surface lies increasingly higher above the water table. In the northernpeninsulatheelevationissufficientlylow that theancientMaya were able toreachthe water table at deep sinkholes called cenotes, or at deep caves. In low-elevation north coastal areas without sinkholes, the Maya would have been able to get down to the water table by digging wells up to 75 feet (22 meters) deep. But much of the south lies too high above the water table for cenotes or wells toreachdown to it. Making matters worse, most of the YucatanPeninsulaconsists of karst, aporoussponge-likelimestoneterrainwhere rain runs straight into the ground and where little or no surface water remainsavailable.

How did thosedensesouthern Maya populationsdealwith the resulting water problem? Itinitiallysurprises us that many of their cities were not built next to the rivers butinsteadon highterrainin rolling uplands. The explanation is that the Maya excavated depressions, or modified natural depressions, and then plugged up leaks in the karst by plastering the bottoms of the depressions in order to create reservoirs, which collected rain from large plastered catchment basins and stored it for use in the dryseason. For example, reservoirs at the Maya city of Tikal held enough water to meet the drinking water needs of about 10,000 people for a period of 18 months. At the city of Coba the Maya built dikes around a lake in order toraiseitsleveland make their watersupplymorereliable. But the inhabitants of Tikal and other cities dependent on reservoirs for drinking water would still have been in deep trouble if 18 months passed without rain in aprolongeddrought. A shorterdroughtin which they exhausted their stored food supplies might already have gotten them in deep trouble, because growing crops required rain rather than reservoirs.

Questions:
question_stem: Why does the author call the Mayan homeland both a “seasonal tropical forest” and "seasonal desert”?
choices: tag: A
text: To illustrate how the climate of the Mayan homeland varied from region to region

tag: B
text: To explain how the climate of the Mayan homeland is similar to that of a jungle or tropical rainforest

tag: C
text: To emphasize the vast size of the area that comprised the Mayan homeland in ancient times

tag: D
text: To make the point that the Mayan homeland is climatically more complex than is generally assumed
answer_key: D
explanation: 功能目的题，修辞点所在的句子只是单纯在说一个例子，所以往前看，前句说有雨季也有旱季，所以对应的是答案 D，MAYA 地区的气候复杂多变。A 的各个地区不同原文没说；B 没说旱季，错；C 说明 maya 地域广大原文没有。

question_stem: Which of the following is NOT mentioned in paragraph 2 as a difference between the northern and southern Yucatan Peninsula?
choices: tag: A
text: The annual rainfall was greater in the south.

tag: B
text: The population density was lower in the north.

tag: C
text: Agricultural productivity was greater in the south

tag: D
text: Rainfall was more unpredictable and variable in the south.
answer_key: D
explanation: D EXCEPT 题，排除法。A 的 rainfall 做关键词定位至第一句，从北到南18到100英寸，明显是北小南大，所以 A 正确，不选；B 的 population density 做关键词定位至第一句，说南部 denser，所以北部密度小正确，不选；C 的 productivity 做关键词定位至第一句，说南部更 productive，正确，不选；所以答案是 D.

question_stem: Which of the following statements about ancient and modem agriculture in the Yucatan Peninsula is supported by paragraph 2?
choices: tag: A
text: Modern agricultural methods have solved many of the ancient problems of farming in the Yucatan Peninsula.

tag: B
text: Ancient Mayan farmers may have been somewhat more successful at farming in the Yucatan Peninsula than farmers are today.

tag: C
text: Farming today is easier than in the past because environmental changes in the Yucatan Peninsula have increased available rainfall

tag: D
text: The Yucatan soils in which ancient farmers worked were richer, more productive, and thicker than they are today.
answer_key: B
explanation: B, 为专有名词出现在第一句，所以整段都在说这个地方，明显不适合做关键词，用 ancient 和 modern 做关键词定位至倒数两句，说现代和古代的玛雅人都会遇到同样的问题，但在某种程度上说，古代人比现代人解决的好，所以答案是 B。A 说现代人解决了以前人的问题，说反；C 和 D 原文都没说。

question_stem: The word “paradoxically” in the passage is closest in meaning to
choices: tag: A
text: usually

tag: B
text: surprisingly

tag: C
text: understandably

tag: D
text: predictably
answer_key: B
explanation: B paradoxically：矛盾地，反常的。A 是通常的；B 是惊人地，出乎意外地；C 是可以理解地；D 是可预测的。所以正确答案是 B。

question_stem: The phrase “The likely explanation” in the passage refers to the explanation for why
choices: tag: A
text: the southern Maya areas received more rainfall than the northern areas

tag: B
text: modern archaeologists have difficulty understanding ancient droughts

tag: C
text: water problems were most severe in the wet south

tag: D
text: land surface in the south is so high above the water table
answer_key: C
explanation: C 问 the likely explanation 解释的是哪个问题，按照常理肯定是给出问题之后才会给出可能的解释，所以往前找，前文提出了一个问题，为什么本来湿润的南部地区的缺水问题比干燥的北部地区更严重，所以答案是 C，如果不确定可以看看=本句的 explanation 的内容，也是解释为什么南部反而缺水的。

question_stem: Which of the following statements about the availability of water in the Mayan homeland is supported by paragraph 3?
choices: tag: A
text: The construction of wells was an uncommon practice in both the north and the south because it was too difficult to dig through the karst.

tag: B
text: In most areas in the north and the south, rainwater was absorbed directly into the porous karst.

tag: C
text: The water table was an important resource for agriculture in both the north and the south of the Yucatan Peninsula.

tag: D
text: The lack of surface water in both the north and the south was probably due to the fact that most of it was quickly used up for agricultural purposes.
answer_key: B
explanation: B 问整段支持下面哪个，所以最好用排除法。A 的 well 做关键词定位至倒数第二句和倒数第三句，原文说北部打井容易，南部难，所以 A 错；B 的 karst 做关键词定位至最后一句，说大部分地区都是岩溶地貌，所以 B 正确；C 的 water table 定位至第三句和倒数第二句，没提到重要性，所以 C 错；D 在原文中完全没有对应.

question_stem: According to paragraph 3, why was the southern Mayan homeland hard to farm?
choices: tag: A
text: The presence of numerous sinkholes and wells interfered with farming.

tag: B
text: Southern soil lacked the depth crops needed for growth.

tag: C
text: Underground water was too far below the surface to reach.

tag: D
text: The presence of karst caused frequent flooding.
answer_key: C
explanation: C 这段中直接提到 south 困境的描述只有第三句和最后两句话，描述了2个特点：1）high above water table，不能够钻井取水；2）高渗透，地表水所剩不多。因此，C 选项正确。A 的 sinkhole 做关键词定位至倒数第四句，原文没说 sinkhole 干扰了农业的发展，所以 A 错；B 在文章中彻底没说，错；D 的 flooding 原文没说。

question_stem: Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
choices: tag: A
text: Southern Maya populations obtained the water they needed for the dry season by collecting and storing rainwater in sealed depressions.

tag: B
text: The Maya are credited with creating methods for modifying natural rainwater and storing it.

tag: C
text: Leaks in the karst caused difficulties in the creation of reservoirs, which were needed to store water for the dry season.

tag: D
text: Southern Mayans were more successful at collecting rain than storing it during dry seasons.
answer_key: A
explanation: A 原文的结构是玛雅人挖了 depression 或者休整了本来就有的 depression 用来装水。A 完全体现了这个结构，正确；B 偷换概念，原文说 modify 的是 depression，不是雨水；C 将原文的主语完全改变，错；原文没有比较，所以 D 错。

question_stem: What can be inferred from paragraph 4 about how residents of Tikal met their needs for water and food during most periods of drought?
choices: tag: A
text: They depended upon water and food that had been stored for use during the dry season.

tag: B
text: They obtained drinking water and water for crop irrigation from Coba dikes.

tag: C
text: They located their population centers near a lake where water was available for drinking and watering crops.

tag: D
text: They moved locations every 18 months to find new croplands and water sources.
answer_key: A
explanation: A 以专有名词和 drought 做关键词定位至倒数第二句，说他们是依靠 reservoir 的，所以答案是 A，they stored；B 的 Coba dikes，C 的 lake 和 D 的 new croplands 都没说。

question_stem: The word "prolonged" in the passage is closest in meaning to
choices: tag: A
text: unusual

tag: B
text: unexpected

tag: C
text: extended

tag: D
text: disastrous
answer_key: C
explanation: C prolonged: 延长的，长期的。A 是不寻常的；B 是意外的；C 是延长的；D 是灾难性的。所以答案 C。

question_stem: The word "exhausted" in the passage is closest in meaning to
choices: tag: A
text: used up

tag: B
text: reduced

tag: C
text: wasted

tag: D
text: relied upon
answer_key: A
explanation: A : exhaust: 消耗，用光。A 是用完，耗尽；B 是减少；C 是浪费；D 是依赖。所以答案是 A。