tpo37阅读文本和题目完整无水印

tpo37阅读文本和题目完整无水印内容摘要：

economies based on trade. 10. The word domestic in the passage is closet in meaning to  Practical  Household  Standard  Necessary 11. According to paragraph 6, why was bronze not used for farming tools in Bronze age civilizations of the Near East  Wooden farming tools were more effective in the soils of the region.  Bronze farming tools would have deteriorated quickly in the climate.  Bronze was too expensive to use for farming tools.  People had not yet discovered how to make farming tools out of bronze. 12. According to paragraph 6, which of the following was true of at least some civilizations of the Bronze Age?  They did not develop urban centers with large populations.  They did not use metals to make bronze.  They had an economy that was not based on agriculture.  They did not use bronze for luxury items such as jewelry. 13. Look at the four squares [■] that indicate where the following sentence could be added to the passage. This significantly limited the availability of bronze. 14. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points. Drag your choices to the spaces where they belong. To review the passage, click on View Text. Answer Choices  Before the rise of large cities with plex economies, there had been no need for any kind of administrative structure to anize workers, and thus religion tended to be the only source of authority.  Large cities functioned as administrative centers, creating a concentration of wealth and resources that stimulated technological advances, such as the invention of writing and the creation of bronze.  By 3000 ., a number of agricultural societies had emerged as civilizations characterized by large cities, centralized administrations, specialization of labor, class divisions, metal technology, and writing.  For a culture to be considered a civilization, it must have independently invented its own form of writing and bee generally literate, thereby moving from prehistory into the historic period.  Although rivervalley societies had to import the metals for making bronze, the first phase of civilization is known as the Bronze Age because of the importance of metal technology in these societies.  The creation of bronze made it possible for civilizations based on largescale agriculture to be located far away from the river valleys and deltas in areas where the soil was less rich and less easy to work. TPO372 Stream Deposits A large, swift stream or river can carry all sizes of particles, from clay to boulders. When the current slows down, its petence (how much it can carry) decreases and the stream deposits the largest particles in the streambed. If current velocity continues to decrease as a flood wanes, for example finer particles settle out on top of the large ones. Thus, a stream sorts its sediment according to size. A waning flood might deposit a layer of gravel, overlain by sand and finally topped by silt and clay. Streams also sort sediment in the downstream direction. Many mountain streams are choked with boulders and cobbles, but far downstream, their deltas are posed mainly of fine silt and clay. This downstream sorting is curious because stream velocity generally increases in the downstream direction. Competence increases with velocity, so a river should be able to transport larger particles than its tributaries carry. One explanation for downstream sorting is that abrasion wears away the boulders and cobbles to sand and silt as the sediment moves downstream over the years. Thus, only the fine sediment reaches the lower parts of most rivers. A stream deposits its sediment in three environments: Alluvial fans and deltas form where stream gradient (angle of incline) suddenly decreases as a stream enters a flat plain, a lake, or the sea。 floodplain deposits accumulate on a floodplain adjacent to the stream channel。 and channel deposits form in the stream channel itself. Bars, which are elongated mounds of sediment, are transient features that form in the stream channel and on the banks. They monly form in one year and erode the next. Rivers used for mercial navigation must be recharted frequently because bars shift from year to year. Imagine a winding stream. The water on the outside of the curve moves faster than the water on the inside. The stream erodes its outside bank because the current39。 s inertia drives it into the outside bank. At the same time, the slower water on the inside point of the bend deposits sediment, forming a point bar. A midchannel bar is a sandy and gravelly deposit that forms in the middle of a stream channel. Most streams flow in a single channel. In contrast, a braided stream flows in many shallow, interconnecting channels. A braided stream forms where more sediment is supplied to a stream than it can carry. The stream dumps the excess sediment, forming midchannel bars. The bars gradually fill a channel, forcing the stream to overflow its banks and erode new channels. As a result, a braided stream flows simultaneously in several channels and shifts back and forth across its floodplain. Braided streams are mon in both deserts and glacial environments because both produce abundant sediment. A desert yields large amounts of sediment because it has little or no vegetation to prevent erosion. Glaciers grind bedrock into fine sediment, which is carried by streams flowing from the melting ice. If a steep mountain stream flows onto a flat plain, its gradient and velocity decrease sharply. As。