托福考试

根据网考网考试中心的统计分析，以下试题在2019/5/21日托福考试习题练习中，答错率较高，为：74%
【分析解答题】Question: Summarize the lecture and explain how weathering can break down rocks by two primary processes: the water or plant growth.
，答错率：74%
网考网试题解析：
试题答案： 答案解析：Weathering can break rocks down in two ways. First, water that enters the joints of rocks can deepen and widen the joints when it reaches its freezing point. As a result, the joints are expanded further by the ice, which finally breaks down the rock. Living organisms such as plants can also break down rocks. For example, plant roots can grow and penetrate into soil or rock layers and force the rock to crack as plants grow bigger. [听力原文] W: Weathering is the breaking down of Earth’s rocks, soils and minerals through direct contact with the planet’s atmosphere. The breakdown rocks follow two primary processes: by either water or plant growth. Weathering by water is common in mountain areas where the temperature is around the freezing point of water. Once the temperature drops below freezing point, the water that has entered the joints of rocks freezes. The expanding ice strains the walls of the joints, and this causes the joints to deepen and widen. This is because the volume of water expands by about ten percent when it freezes. As a result, the ice enlarges the joints further. The ice crystal growth weakens the rocks which, in time, break up. In other words, the breaking down is caused by the expansion of ice when water freezes, which puts considerable stress on the walls of its container. Living organisms such as plants can also contribute to mechanical weathering. For example, the roots of a plant growing down into the rock is a mechanical weathering agent which can penetrate many meters through the different soil layers to force or wedge into cracks. As the plant grows bigger, it will eventually break the rock into pieces. document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>