2017-05-08
为了帮助大家更好的备考PTE考试，下面为大家准备的PTE听力高频考题：Fill in the blanks填空。
PTE听力薄弱的同学赶紧来看看吧。
1. delta 形成的过程 地理
River deltas form when a river carrying sediment reaches either (1) a body of standing water, such as a lake, ocean, or reservoir, (2) another river that cannot remove the sediment quickly enough to stop delta formation, or (3) an inland region where the water spreads out and deposits sediments. The tidal currents also cannot be too strong, as sediment would wash out into the water body faster than the river deposits it. Of course, the river must carry enough sediment to layer into deltas over time. The river's velocity decreases rapidly, causing it to deposit the majority, if not all, of its load. This alluvium builds up to form the river delta. When the flow enters the standing water, it is no longer confined to its channel and expands in width. This flow expansion results in a decrease in the flow velocity, which diminishes the ability of the flow to transport sediment. As a result, sediment drops out of the flow and deposits. Over time, this single channel builds a deltaic lobe (such as the bird's-foot of the Mississippi or Ural river deltas), pushing its mouth into the standing water. As the deltaic lobe advances, the gradient of the river channel becomes lower because the river channel is longer but has the same change in elevation (see slope).
As the slope of the river channel decreases, it becomes unstable for two reasons. First, gravity makes the water flow in the most direct course down slope. If the river breaches its natural levees (i.e., during a flood), it spills out onto a new course with a shorter route to the ocean, thereby obtaining a more stable steeper slope.[3] Second, as its slope gets lower, the amount of shear stress on the bed decreases, which results in deposition of sediment within the channel and a rise in the channel bed relative to the floodplain. This makes it easier for the river to breach its levees and cut a new channel that enters the body of standing water at a steeper slope. Often when the channel does this, some of its flow remains in the abandoned channel. When these channel-switching events occur, a mature delta develops a distributary network.
Another way these distributary networks form is from deposition of mouth bars (mid-channel sand and/or gravel bars at the mouth of a river). When this mid-channel bar is deposited at the mouth of a river, the flow is routed around it. This results in additional deposition on the upstream end of the mouth-bar, which splits the river into two distributary channels. A good example of the result of this process is the Wax Lake Delta in Louisiana.
In both of these cases, depositional processes force redistribution of deposition from areas of high deposition to areas of low deposition. This results in the smoothing of the planform (or map-view) shape of the delta as the channels move across its surface and deposit sediment. Because the sediment is laid down in this fashion, the shape of these deltas approximates a fan. The more often the flow changes course, the shape develops as closer to an ideal fan, because more rapid changes in channel position results in more uniform deposition of sediment on the delta front. The Mississippi and Ural River deltas, with their bird's-feet, are examples of rivers that do not avulse often enough to form a symmetrical fan shape. Alluvial fan deltas, as seen by their name, avulse frequently and more closely approximate an ideal fan shape.
2. 有个填空是“just in time”好像是og里的SWT→_→但是不确定是不是同一个句子
3. ethical/democracy/irrelevant/fatality/helmet
4. underlined, modes, assume, muscle,
5. profit maximization
6. acidic red, colours and design
7. 有个地方每年都有很多游客，后来又一次，恐怖袭击造成的混乱，separatist 的什么开始了，来这儿的游客都在冒生命危险，最后一个单词是lives，看到最后才知道前面在讲什么鬼
8. 有个填空题是讲新能源的，我好像hydrogen多打了1个
9. similar，relevant
10. onion：洋葱在印度为何popular
11. Necessarily
12. Challenge
13. Editorial
14. Library
15. Citizenship
16. Curriculum
17. Legislative
18. Government
19. Spectrum
20. Aspect
21. Sales
22. Permanent
23. Journalist
24. Relief
25. Recession
26. Added
27. Failure
28. Incorporate
29. Intend
30. Determination
31. Laid off
32. Overseas
33. ridiculous
34. convergence
35. microbes
36. molecules
37. self(-assessment)
38. five/fifth
39. 26
希望大家都能够在PTE考试中取得理想的成绩。
