(单词翻译:单击)
题型:填空,地图,配对,选择
S1 海岛酒店预订booking an island hotel accommodation
S2 地图题
S3 工厂实习评价反馈the main job tasks for man named Alex during the internship of a company, the comments from the boss and self reflection.
S4 fossil(化石)保护方法
其中,S4有一定难度。虽然考试本身不要求了解相关地质学知识,但有一点背景知识会有助于更快把握要点,找到脉络。所以平时训练中注意各类人文科普知识的积累,是备考的重要手段之一。这里摘抄维基百科中关于fossil的一些介绍,能够帮助理解文中提到的一些概念。
Fossils are the preserved remains ortraces of animals, plants, and other organisms from the remote past. The totality of fossils, both discovered and undiscovered, and their placement infossiliferous(fossil-containing) rock formations and sedimentary layers (strata) is known as thefossil record.
Permineralization is a process of fossilization that occurs when anorganism is buried. The empty spaces within an organism (spaces filled withliquidor gas during life) becomefilled withmineral-rich groundwater. Minerals precipitate from the groundwater, occupying the empty spaces. This process can occur in very small spaces, such as within the cell wall of a plant cell. Small scale permineralization can produce very detailed fossils. For permineralization to occur, the organism must becomecovered by sedimentsoon after death or soon after the initial decay process. Thedegreeto which theremains are decayedwhen covered determines the later details of the fossil. Some fossils consist only of skeletal remains or teeth; other fossils contain traces of skin, feathers or even soft tissues. This is a form of diagenesis.
Paleontology seeks to map out how life evolved across geologic time. A substantial hurdle is the difficulty of working out fossil ages. Beds that preserve fossils typically lack the radioactive elements needed for radiometric dating. This technique is our only means of giving rocks greater than about 50 million years old an absolute age, and can be accurate to within 0.5% or better. Although radiometric dating requires careful laboratory work, its basic principle is simple: the rates at which various radioactive elements decay are known, and so theratioof the radioactive element to itsdecay productsshows how long ago the radioactive element was incorporated into the rock. Radioactive elements are common only in rocks with a volcanic origin, and so the only fossil-bearing rocks that can be dated radiometrically are volcanic ash layers.