tpo green icebergs第七题求解。谢谢

rainandcmUID: 2442269

A green iceberg that stranded just west of the Amery Ice Shelf showed two distinct layers: bubbly blue-white ice and bubble-free green ice separated by a one-meter-long ice layer containing sediments. The green ice portion was textured by seawater erosion. Where cracks were present, the color was light green because of light scattering; where no cracks were present, the color was dark green. No air bubbles were present in the green ice, suggesting that the ice was not formed from the compression of snow but instead from the freezing of seawater. Large concentrations of single-celled organisms with green pigments (coloring substances) occur along the edges of the ice shelves in this region, and the seawater is rich in their decomposing organic material. The green iceberg did not contain large amounts of particles from these organisms, but the ice had accumulated dissolved organic matter from the seawater. It appears that unlike salt, dissolved organic substances are not excluded from the ice in the freezing process. Analysis shows that the dissolved organic material absorbs enough blue wavelengths from solar light to make the ice appear green.
7.
Why does the author mention that “The green ice portion was textured by seawater erosion”?
○To explain why cracks in the iceberg appeared light green instead of dark green
○To suggest that green ice is more easily eroded by seawater than white ice is
○To support the idea that the green ice had been the bottom layer before capsizing
○To explain how the air bubbles had been removed from the green ice
答案给的是c，不是很明白，求解。谢谢啦。
大家节日快乐

crysmileUID: 2528832

需要结合上一段理解Green Iceberge的成因。
第四段最后一句： The scientists concluded that green icebergs form when a two-layer block of shelf ice breaks away and capsizes (turns upside down), exposing the bubble-free shelf ice that was formed from seawater. 科学家得出结论，当一块两层的陆架冰断裂时，会发生翻转（原先的底部朝上），露出在海水中形成的没有气泡的陆架冰。

作者提到“The green ice portion was textured by seawater erosion”  冰川的绿色部分呈现出被海水侵蚀过所留下的印迹，就是为了证明绿色冰川是在海水中形成的，（C项： the green ice had been the bottom layer before capsizing），也就是说：在陆架冰没有发生翻转之前，绿色部分位于底部（即是浸泡在海水中的）。

第四段先提出理论，然后第五段进一步解释了各方面的证据（绿色冰川形成的过程、成因）：
（1）绿色部分有被海水侵蚀过的证据，并且不存在气泡；
（2）海洋中的单细胞生物分解形成绿色的有机质，溶解在海水中，被冰川吸收；
（3）冰川中的有机物质会吸收阳光的蓝色波长，使冰川呈绿色。

：）

generalidUID: 2824377

弱弱的说，green icebergs 是我在黄金阅读里面做过最难的，难的我第一遍基本上看不懂，别太在意这篇文章。
基本上考试不会这么太变态的。

crysmileUID: 2528832

做一些比考试稍难的题目还是有必要的吧，如果你把水平提高到能应对一点难题，那样做相对简单的题目时就会更得心应手，至少不会有损失的~:loveliness:

想把总分提高到100，最好把水平提高到105，那样成绩就不会受客观波动因素的影响了，也是同样的道理

rainandcmUID: 2442269

谢谢啦