2021年全国英语二级阅读理解强化练习.doc

2021年全国英语二级阅读理解强化练习 【导语】锲而舍之，朽木不折；锲而不舍，金石可镂。备考需要这样持之以恒的精神。小编为您提供了“202*年全国英语二级阅读理解强化练习”，欢迎阅读参考！更多相关讯息请关注小编！ 　　Passage 1 　　Over a hundred years ago in 1911,something strange was found in the glaciers of Antarctica.Crilffith Taylor—an Australian geologist,had discovered a blood red stream pouring out of the ice cascades (瀑布) of Talor Glacier!Popularly known as the Blood Falls,scientists had not been able to find the reason behind the blood red liquid flowing through the ice—until recently.The mystery of the Blood Falls had finally been solved. 　　When these falls were first discovered,scientists had believed that the red colour came from a large amount of red algae (海藻) concentrated in the water.Red algae contain a pigment (色素) which reflects red light,making the algae appear red. 　　This theory made sense,until it was later found that algae do not play a part in the red color of the flowing liquid at all.What really causes Talor Glacier’s waters appear blood red,is the presence of iron oxide in the liquid.The waters of the Blood Falls are rich in salt and iron content,and when this water comes in contact with the air,it turns red—just like rust!The water in these falls is often referred to as “brine” by scientists because of the high salt content in the water. 　　This reasoning behind the red colors of the falls was found back in 2003.However,the entire mystery had not yet been solved.How is it then,that the Blood Falls are not frozen? 　　Researchers at the University of Colorado and University of Alaska found that inside the glacier,there is a network of channels and reservoirs that move the water around.Salt water has a lower freezing temperature.In addition,when any substance undergoes a change in state,it gives off heat.Therefore,the brine actually warm itself up while it’s freezing!How this works,is that when the brine is flowing through the Talor Glacier,some of it does freeze.As a result of changing state from liquid to ice,the brine gives off heat.This heat is eno