【導(dǎo)讀】TPO37-1. characterist

　　

【正文】 sharply. As a result, it deposits most of its sediment in a fanshaped mound called an alluvial fan. Alluvial fans are mon in many arid and semiarid mountainous regions. 7. According to paragraph 3, all of the following are true of braided streams EXCEPT: ? They shift back and forth on the floodplain as some of their channels fill with sediment and new ones are formed. ? They carry sediments that tend to be very similar in size. ? They sometimes have midchannel bars. ? Some of their channels are created as a result of the overflow of other channels. 8. Why does the author include the information that Glaciers grind bedrock into fine sediment, which is carried by streams flowing from the melting ice? ? To give a reason why heavily sedimented braided streams are mon in glacial environments ? To explain why some mountain streams deposit most of their sediment in a fanshaped mound ? To identify the most mon source of sediment in arid and semiarid mountainous regions ? To help explain why glacial sediment decreases the gradient and velocity of steep mountain streams 9. The word “simultaneously” in the passage is closest in meaning to ? In many directions ? On the surface ? At the same time ? In a straight line Paragraph 4: A stream also slows abruptly where it enters the still water of a lake or ocean. The sediment settles out to form a nearly flat landform called a delta. Part of the delta lies above water level, and the remainder lies slightly below water level. Deltas are monly fanshaped, resembling the Greek letter delta (!〇 ). Both deltas and alluvial fans change rapidly. Sediment fills channels (waterways), which are then abandoned while new channels develop as in a braided stream. As a result, a stream feeding a delta or fan splits into many channels called distributaries. A large delta may spread out in this manner until it covers thousands of square kilometers. ■Most fans, however, are much smaller, covering a fraction of a square kilometer to a few square kilometers. ■The Mississippi River has flowed through different delta channels during the past 5,000 to 6,000 years. ■But in recent years, engineers have built great systems of levees (retaining walls) in attempts to stabilize the channels. ■ 10. The word “abruptly” in the passage is closest in meaning to ? Noticeably ? Gradually ? Suddenly ? Slightly 11. According to paragraph 4, what is true about river deltas? ? They alternate between periods of spreading out and periods of getting smaller. ? They have both active channels and channels that have been blocked by sediment. ? They are typically formed by rivers that are braided before they reach the delta area. ? They are much larger when formed in a still lake than when formed in the ocean. 12. According to paragraph 4, what are engineers trying to acplish in the Mississippi delta ? To expand the channels into which the river flows ? To keep the river flowing in the existing channels ? To control the amount of sediment the river brings to the delta ? To increase the part of the delta that lies above water level 13. Look at the four squares [■] that indicate where the following sentence could be added to the passage. If the Mississippi River were not contained by such systems, it would probably abandon its present path and cut into the channel of a nearby river to the west. 14. Directions: An introductory sentence for a brief summary of the passage 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 answer choices 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. Answer Choices ? Particles tend to be largest upstream and smallest downstream, probably because water flowing downstream erodes fine sediment from the larger particles. ? A wide variety of deposits, including bars, alluvial fan s, and deltas, are formed as a result of an increase in the speed of the downstream current. ? Bars monly shift from being point bars on a river bank to being midchannel bars. ? Deposits of sediment are found where flow velocity decreases, and when there is excessive sediment a stream may bee braided, dividing into several channels. ? Rivers that flow through arid and semiarid mountainous regions tend to form alluvial fans at bends in the river. ? Deltas, which are formed where streams enter lakes or the ocean, are naturally unstable landforms that can extend over a large area TPO373 Characteristic of roman pottery The pottery of ancient Romans is remarkable in several ways. The high quality of Roman pottery is very easy to appreciate when handling actual pieces of tableware or indeed kitchenware and amphorae (the large jars used throughout the Mediterranean for the transport and storage of liquids, such as wine and oil). However, it is impossible to do justice to Roman wares on the page, even when words can be backed up by photographs and drawing. Most Roman pottery is light and smooth to touch and very tough, although, like all pottery, it shatters if dropped on a hard surface, it is generally made with carefully selected and purified clay, worked to thinwalled and standardized shapes on a fast wheel and fired in a kiln (pottery oven) capable of ensuring a consistent finish. With handmade pottery, inevitably there are slight differences between individual vessels of the same design and occasional minor blemishes (flaws). But what strikes the eye and the touch most immediately and most powerfully with Roman pottery is its consistent high quality. This is not just an aesth