第一篇：铸币业minting
由于银矿的发现，铸币业开始产生。中世纪商人可以仅携带少量银币出行，促进了长途贸易的发展。由此，商业行会形成，商人之间mutual trust刺激credit机制的产生。
Medieval minting
Alterations in the flan (the coin disk, a term deriving from the French flatir, “to beat flat”) led to corresponding changes in the manufacture of dies. In about AD 220 the Sāsānian dynasty of Iran introduced the concept of thin flan coins, issues that were struck in relief on both sides. In order not to produce intolerable stresses in the dies, since the thinner the material the more force necessary to make it flow into the recesses of the die's design, the depth of relief on such coins was of necessity much shallower than with earlier currency. Such techniques spread by way of Byzantium to northern Europe, where the emperor Charlemagne struck thin flan deniers (small silver coins), or pennies, which became characteristic of both his own and neighbouring kingdoms.
The Franks and Saxons inherited an art that was formalistic rather than realistic, and this permitted their coin designs to be made up from a small number of standard elements that were reproducible using punches. It has been shown, for example, that the complete dies for all of the coin types of Edward the Confessor of England could be obtained from seven punches, giving individual wedges, crescents, pellets, and bars, each of which was independently struck to make up a legend and design. Consequently, a single workshop could supply the 70 or so contemporary English mints in a relatively short time. An experimental pair of dies took less than an hour to fabricate. Of course, many European dies were produced by a combination of punching and engraving, while engraving alone was typical of early Islamic and contemporary Oriental dies. With the advent of larger denominations, such as the gros tournois (based on the weight standard of Tours, in France) in the 13th century, more florid designs came to be preferred, but the elements of the royal crown, for example, or the letters of the legend were still punched into the dies. To judge from surviving specimens, both upper and lower dies (trussells and piles) were by then produced from wrought iron. While the upper die retained the cylindrical shape of antiquity, the lower die was tanged (having protrusions added) so that it could be wedged into a wooden block.
The thin silver sheet required for the new coins needed to be beaten out from its cast state, and this in turn necessitated annealing (strengthening by slow cooling) to prevent cracking. By the 10th century, squares of sheet, somewhat larger than the eventual penny, were being struck between square dies and then separated by a circular cutter. A few imitative coins on square flans are known from Scandinavia, while die identical coins have exactly matching edge irregularities, proving use of the same cutter. With the introduction of the gros tournois, the blanks were cut roughly circular with shears, then gripped by special tongs in rouleaux (columnar rolls) of a dozen or more, and finally hammered into circularity on a flat anvil. Alternatively, the silver was cast into thin rods of rectangular section; pieces of the correct length (and hence weight) were next cut from the rod by chisel and then, with several annealings, were beaten to the appropriate thickness, before being rounded and struck by a die. Blanching (cleaning) of the blanks by an acid dip was necessary before striking to produce an acceptable surface if oxidation had occurred during annealing.
Striking was carried out in much the same way as during antiquity, although contemporary illustrations indicate that only one operator, not a team, was employed. Twelfth-century Byzantine coins were often cup shaped. A full impression of the curved dies could not easily be obtained by one blow; hence there evolved a method of striking one half of the coin with a slightly inclined upper die, which was then rocked over to the other side for a second blow. Bracteates, issues of foil thickness, were common in 12th-century Germany. To make these, a single die was used to strike a column of several blanks resting on a piece of leather, so that the reverse of each was the incuse (hollowed impression) of the obverse. Die life in general was higher than during antiquity, and documentary evidence for 13th-century English pence indicates perhaps 30,000 coins per obverse. There is no evidence for production rates.
第二篇：猛犸与草原Mammoth Steppe
白令海域在过去2.5万年之间有七次冷暖交替，猛犸象在最后一次灭绝。学者G认为一种名为Mammoth Steppe的草在气候寒冷时期，除了最冷的较短时间段外，成长状况都非常好，甚至好于现代的草，足成为猛犸充足的食物来源。现代植物由于ph值偏低，以及其他诸多原因，作为食物质量较差，不适合猛犸食用。因此，合理的推论是Mammoth Steppe的灭绝与猛犸灭绝有某种联系。有反对者认为Mammoth Steppe的存在缺乏化石证据的支持，因此这种草和猛犸的联系也可疑。另有叙述：草原的繁盛或许与猛犸的踩踏有关——灌木被破坏，难以与草本植物抢养分。但这种观点也因为化石证据有限而可疑。
mammoth
any member of an extinct group of elephants found as fossils in Pleistocene deposits over every continent except Australia and South America and in early Holocene deposits of North America. (The Pleistocene Epoch began 2.6 million years ago and ended 11,700 years ago. The Holocene Epoch began 11,700 years ago and continues through the present.) The woolly, Northern, or Siberian mammoth (M. primigenius) is by far the best-known of all mammoths. The relative abundance and, at times, excellent preservation of this species' carcasses found in the permanently frozen ground of Siberia has provided much information about mammoths' structure and habits. Fossil mammoth ivory was previously so abundant that it was exported from Siberia to China and Europe from medieval times. Scientific evidence suggests that small populations of woolly mammoths in North America may have survived until between 10,500 and 7,600 years ago.
Mammoths figured significantly in the art of primitive humans; cave dwellers in Europe realistically depicted herds of these animals. Mammoths were sometimes trapped in ice crevasses and covered over; they were frozen, and their bodies were remarkably well preserved. In fact, cases have been reported in which sled dogs actually were fed the meat from frozen mammoth carcasses that had begun to thaw out of the ice that had held them for almost 30,000 years.
A variety of distinct species are included in the genus Mammuthus. Most mammoths were about as large as modern elephants. The North American imperial mammoth (M. imperator) attained a shoulder height of 4 metres (14 feet). At the other extreme were certain dwarfed forms whose ancestors became isolated on various islands. Many mammoths had a woolly, yellowish brown undercoat about 2.5 cm (1 inch) thick beneath a coarser outer covering of dark brown hair up to 50 cm (20 inches) long. Under the extremely thick skin was a layer of insulating fat at times 8 cm (3 inches) thick. The skull in Mammuthus was high and domelike. The ears, small for an elephant, were probably adaptively advantageous for an animal living in a cold climate; the smaller amount of exposed surface area diminished heat losses. A mound of fat was present as a hump on the back. This structure is lacking in fossil remains, but evidence for its presence comes from cave paintings. The prominent tusks were directed downward and were very long; in older males they sometimes curved over each other. Mammoth dentition was made up of alternating plates of enamel and a denture that often became worn down by constant back-to-front chewing motions. Remains of arctic plants have been found in the digestive tracts of frozen mammoth carcasses. It is clear that the mammoth was hunted by early North American hunters.
第三篇：群居的劣势
群居通常被认为是一种较为先进的生物社群组织结构，但这种观点可疑——独居也有很多优势。群居的坏处，有两点：1、群居动物需要耗费精力争夺社会阶层social rank。2、另外群居也比较容易有传染病。但是整体上，某一物种进化到群居状态，则群居的利益必然大于独居，反之亦然——文中有实例支持这一观点。
若干词汇题
Tactic=strategy
Potential=possible
Inhibit=prevent