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托福口语经典话题解析：two ways weathering occurs
Listening Part:
听力原文:
Listen to part of a lecture in a geology class.
(female professor)
Rocks near the Earth’s surface are directly exposedto elements in the environment such as air andwater, and also to conditions such as temperature change as well as to living organism. Andthis exposure to the environment can actually cause even huge rocks to break into smallerpieces. This process is called weathering. Let’s talk about a couple ways weathering occurs.
First of all, rocks are often exposed to water. In cold wet environments rocks can break due towater freezing inside of them. How does this happen? Well, as I am sure you know, when waterfreezes it expands and over time this can lead to weathering.
Um, imagine a rock with a small opening or crack in it. It rains and water gets into the crackand stays there. Then, at night, the temperature drops and water inside the crack freezes.This growing, expanding ice pushes outward on either side of the crack causing it to getslightly bigger. When this happens again and again, the crack becomes larger and eventuallypieces of the rock break off.
OK, weathering can also be caused by plants, by a plant growth. If a plant seed gets blown intothe crack of a rock, it may take root. And its root will grow down into the rock. The plant’sroots can cause the rock to break down, uh, fracture. You may have seen this with large treesgrowing on top of a rock, a great example of this. Usually there’s enough dirt in a crack of arock or on top of a rock to allow a tree to start growing there. As the tree grows over theyears, the tree’s roots extend downward into the crack and crevasses of the rock in search ofwater and nutrients. Over time, the roots get bigger and grow deeper, widening and enlargingthe cracks, causing the rock to break apart.
Question:
Using point and examples from the lecture, explaintwo ways weathering occurs.
Listening keys:
本题属于Task6当中的举例子题。Task6与Task4不同之处在于1)一定是‘一拖二’模式 2)需要根据listening过后提出的问题来回答。很多同学不知道Task6如何开头，实际就像前面所说的，根据问题回答。比如题目问‘using the examplesfrom the lecture, explain two types of …’，回答的时候就以‘There are two types of …’开头。 这道题本身不难理解，如果懂一些简单的生物物理知识就更容易把握。但是lecture中教授语速较快，可能造成笔记混乱或者记不下来。因此要求大家用流程图的形式记笔记，便于逻辑清晰地表达。
The professor explains two ways weathering occurs.Firstly, the exposure to water, which means that therock breaks because of freezing water inside it whichwould then expand. To be more specific, if the rainsget into cracks, it will freeze due to lowtemperature. Then the growing expanding icepushes outward, causing the rock to break off little by little. The second way of weatheringhappens under plant growth, which means after the plant seeds get down to take a root, it willgrow into the rock, causing it to fracture. A good example for it is big trees growing on the topof a rock. They gradually extend down their roots for nutrients and water, as a result,widening and enlarging the cracks they grow and breaking it apart at last.
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