Geographicalconstraints have had important consequences for theeconomyand society of Iran. Whererainfallisadequate, there arefertilevalleys and grasslandssuitableforgrazinganimals. However, since the naturalvegetationtends to besparse, it is difficult for such animals toremainin one place for any length of time. Thusnomadicpastoralism—keepinglivestock(such as sheep and goats) by wandering from place to place—was one of the first and mostpersistenthumaneconomicactivities toflourishin this area. Thisnomadicmovement was often of theverticalvariety, with people and animals moving from lowlands in wintertime to highlands in summer. The animals raised by the pastoralists provided not only food but alsomaterialfor crafts such as the making of carpets, thick felt cloth, and tents. The pastoralists were typically organized into largetribalconfederationscapableof controlling thevastterritories needed for maintaining their herds.

The tribes were a powerful social andpoliticalfactorthroughoutIranianhistory. The skills necessary for herding animals, hunting and chasing off predators, directing migrations, disciplining tribesmen, and protecting lands and animals from rivals could be easily adapted and directed towardmilitarypurposes as well. It was typically the tribes that produced the soldiers and rulers of the country and provided the power base for most of its dynasties. Once established, governments needed tocultivatethe support of friendlytribalgroups and tried to controlhostiletribes bycombat, deportation, or forciblesettlement. At the beginning of the twentiethcentury,approximatelyone-fourth of thepopulationweretribalpeoples, and they were apotentforce in Iranian affairs. With theadventof mechanized armies in the 1930s, however, there weresystematicefforts tobreakthe power of the tribes and tocoercethetribalpopulationinto asedentaryway of life. These efforts have been largely successful, and the tribes are no longer sosignificanta force in either the Iranianeconomyor society. Less than 5 percent of thepopulationnow consists ofnomadicpastoralists.

The aridity of the Iranianplateauretarded its agriculturaldevelopmentincomparisontoadjacentregions such asMesopotamia, which had great rivers todrawupon for asupplyof water. Eventually, at some uncertaindateprobably about 26 centuries ago, there was atechnologicalbreakthroughthat made it possible to farm crops outside the few oases, streams, and other places withsufficientrainfallforagriculture. This was thedevelopmentofundergroundcanals known as qanats. The qanat system tookadvantageof the naturalslope(inclination) of theplateaubasins. A well would be dug in the foothills toreacha watersource, usually water frommeltingsnow that had seepedunderground. Then asequenceof wells and shafts connected byundergroundcanals would be constructed totransportthe water to an areasuitableforcultivation, where it could support the needs of one or more villages. Theslopeof theundergroundcanals had to be controlled carefully to preventerosion, and theinteriorsurface of wells and shafts needed to be kept underconstantmaintenanceto prevent them from collapsing.

Since the canals wereunderground, loss fromevaporationwas minimized. Gravityprovided the means of moving the water, so nomechanicalenergy was required tooperatethe system. Thenumerouswells and shafts kept the length of the trickyundergroundcanalshort and facilitated repairs of eachsegment. Built up over the centuries, the systemeventuallybecameimmense. It has been estimated that the total length of the qanat system today, counting wells, shafts, and canals, is inexcessof 300,000 kilometers (almost the distance from Earth to the Moon!), which gives some idea of thetremendousinvestment in money and labor power it represents. Yet the type ofagriculturethat developed around the qanat system gavemodestyields and required hard work from the peasant farmers, who received only a small share of the agricultural produce.

Questions:
question_stem: According to paragraph 1, pastoralists in Iran needed to move their animals for which of the following reasons?
choices: tag: A
text: Their herds were constantly growing in size.

tag: B
text: Much of the land was too steep to be used by all the grazing animals at once.

tag: C
text: In any given place, the animals soon ran out of food.

tag: D
text: Many fertile valleys and grasslands could be reached only at certain times of the year.
answer_key: C
explanation: 题干问 move their animals 的原因是什么。根据关键词 animals 定位到第2句话，提到了 suitable for grazing animals 的原因，不符合，再往后看，出现了转折关系，可能出现不适合的 grazing animals 的情况了，大意为：自然植被逐渐稀疏，动物很难在一个地方停留任何一段时间，也就是动物需要移动。故而原因应该是 natural vegetation tends to be sparse，也就是动物的食物缺乏，故而答案选 C。A 未提到；B 未提到地形；D 中 could be reached only at certain times of the year 这一点文章未提及。

question_stem: According to paragraph 2, nomadic pastoralists were important in Iranian history for all of the following reasons EXCEPT
choices: tag: A
text: They produced rulers for Iran.

tag: B
text: They formed a significant proportion of the Iranian population.

tag: C
text: They used the skills developed for nomadic pastoralism to support ruling dynasties.

tag: D
text: They helped make the transition in Iran from traditional to mechanized armies.
answer_key: D
explanation: 题目问哪个选项不是 nomadic pastoralists 重要的原因。A 对应到第3句话中的 produced the soldiers and rulers of the country，排除；B 对应的到第5句中 approximately one-fourth of the population were tribal peoples，排除；C 对应到第2句中的 The skills…could be easily adapted and directed toward military purposes as well，排除。D 选项 transition in Iran from traditional to mechanized armies 这一点文中未提到。

question_stem: Which of the following can be inferred from paragraph 2 about the relationship between Iranian governments and the nomadic tribes?
choices: tag: A
text: Governments used soldiers from friendly tribes to combat tribes opposed to the government.

tag: B
text: Governments tried to increase the military power of the tribes.

tag: C
text: Governments used the pastoral skills of tribesmen to benefit the governments’ economic interests.

tag: D
text: Governments encouraged fighting amongst the tribes in order to limit tribal power.
answer_key: A
explanation: 题干要求推 Iranian governments 和 the nomadic tribes 之间的关系。根据关键词 Iranian governments、tribes 定位到第4句，该句提出了两者之间的关系：1.governments needed to cultivate the support of friendly tribal groups，2. governments tried to control hostile tribes by combat, deportation, or forcible settlement。对照选项，符合的为 A 选项。B 选项与该段第6句中提到的 systematic efforts to break the power of the tribes 表述相反，不对；C 中提到的 governments’ economic interests 文章未提到；D 中 encouraged fighting amongst the tribes 文章未提及。

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

tag: B
text: opportunity

tag: C
text: advance

tag: D
text: method
answer_key: C
explanation: breakthrough 释义为“突破，突破性进展”，C：发展、进展，符合；A：实验、试验；B：机会；D：方法、方式；故而选 C。

question_stem: According to paragraph 3, why was it necessary to regularly inspect the qanat system?
choices: tag: A
text: Erosion might cause the canals to slope.

tag: B
text: Runoff from melting snow could sometimes cause flooding.

tag: C
text: Wells and shafts might collapse if not kept in good repair.

tag: D
text: Water from the system was not always distributed fairly among villages.
answer_key: C
explanation: 题干问定期检查 qanat system 的原因。无法直接根据关键词定位信息，可根据 regularly inspect 的同义转述进行定位，定位到最后一句话，to be controlled carefully、to be kept under constant maintenance 等词替换了 regularly inspect。该句大意为 controlled carefully 以及 constant maintenance 的目的是为了防止侵蚀和防止坍塌。故而答案对应为 C。A 中的 cause the canals to slope 未提及；B 未提及；D 中的 not distributed fairly among villages 这一点未提及。

question_stem: According to paragraph 4, why was the qanat system built with numerous wells and shafts?
choices: tag: A
text: To minimize water loss

tag: B
text: To keep individual segments of the qanat canals short for easy maintenance

tag: C
text: To avoid the need to supply energy to transport water through the qanat canals

tag: D
text: To provide sufficient means for removing the water for irrigation
answer_key: B
explanation: 题干问 qanat system 有大量的 wells and shafts 的原因。根据关键词 wells and shafts 定位到第3句，kept the length of the canal short and facilitated repairs of each segment，即可以让 canal 的长度较短，便于维修，符合的为 B 选项。A 是第1句提到的 canal 处在地下的结果，不符合；C 并不是 numerous wells and shafts 的原因，而是 Gravity provided the means of moving the water 的结果，不符合；D 文章未提及。

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: The qanat system today is thought to be in excess of 300,000 kilometers, which is almost as great as the distance between Earth and the Moon.

tag: B
text: Counting all of the wells, shafts, and canals would be both difficult and expensive, so the total length of the qanat system has been estimated rather than measured.

tag: C
text: The effort and expense required to build the qanat system is apparent from its estimated length of more than 300,000 kilometers.

tag: D
text: The investment of money and labor needed to construct the qanat system was probably almost as great as that required to travel from Earth to the Moon.
answer_key: C
explanation: 原句核心意思为：如今坎儿井系统的总长度超过了30万公里，说明了金钱和劳动力的投入巨大。A 选项未提及“金钱和劳动力投入巨大”这一信息，排除；B 选项中 Counting would be both difficult and expensive 以及 the total length of the qanat system has been estimated rather than measured 这两层意思都是原句未提及的，完全改变了原句的核心意思，排除；C 的大意为从长度的估算中明显看出劳动力和金钱投入的巨大，符合原句核心意思，C 正确；D 选项中 as great as that required to travel from Earth to the Moon 这一比较错了，排除。

question_stem: In paragraph 3, why does the author compare the agricultural development of the Iranian plateau with that of adjacent regions?
choices: tag: A
text: To explain how rivers affect agricultural development

tag: B
text: To explain why adjacent regions did not develop a qanat system

tag: C
text: To provide the motivation for the development of the qanat system in Iran

tag: D
text: To imply that in both the Iranian plateau and Mesopotamia, agriculture depended on irrigation
answer_key: C
explanation: 定位题干信息到第三段第1句，指出了跟 adjacent regions 相比，Iranian plateau 缺水，农业发展受阻。结合后文进行理解，第2句话指出某项技术突破使得干旱地区的农业发展有可能，该技术突破就是 qanat system。故而作者提到第一句话中的比较点的目的就是为了提出发展 qanat system 的原因，符合的选项为 C：提供了发展 qanat system 的动机。A 中的 how rivers affect agricultural development 文章未提及；文章也未提及 adjacent regions did not develop a qanat system；D 选项中提到的 agriculture depended on irrigation 并不是这段后文所讨论的信息。