智课网TOEFL备考资料
托福TPO阅读真题全套【译文+解析】
摘要： 托福tpo阅读真题全套【译文+解析】下载，不少参加托福考试的牛人考前都会将托福tpo阅读真题全套内容看个2-3遍，真正吃透以里面的内容，你看了吗？
固定工作 uwb超宽带
《论语》十二章 托福 tpo阅读真题全套【译文+解析】全部是之前考试过得真题，它里面的题目的出题点和难度与真题非常接近，是我们参加 托福考试 的考生必不可少的精华材料，下面我们就来看一下有关托福tpo阅读真题的部分内容。
网件路由器 托福tpo阅读真题全套:TPO24
Fossil Prervation
When one considers the many ways by which organisms are completely destroyed after death, it is remarkable that fossils are as common as they are. Attack by scavengers and bacteria, chemical decay, and destruction by erosion and other geologic agencies make the odds against prervation ver
y high. However, the chances of escaping complete destruction are vastly improved if the organism happens to have a mineralized skeleton and dies in a place where it can be quickly buried by diment. Both of the conditions are often found on the ocean floors, where shelled invertebrates (organisms without spines) flourish and are covered by the continuous rain of dimentary particles. Although most fossils are found in marine dimentary rocks, they also are found in terrestrial deposits left by streams and lakes. On occasion, animals and plants have been prerved after becoming immerd in tar or quicksand, trapped in ice or lava flows, or engulfed by rapid falls of volcanic ash.
对别人的评价
The term "fossil" often implies petrifaction, literally a transformation into stone. After the death of an organism, the soft tissue is ordinarily consumed by scavengers and bacteria. The empty shell of a snail or clam may be left behind, and if it is sufficiently durable and resistant to dissolution, it may remain basically unchanged for a long period of time. Indeed, unaltered shells of marine invertebrates are known from deposits over 100 million years old. In many marine creatures, however, the skeleton is compod of a mineral variety of calcium carbonate called aragonite. Althou
gh aragonite has the same composition as the more familiar mineral known as calcite, it has a different crystal form, is relatively unstable, and in time changes to the more stable calcite.
Many other process may alter the shell of a clam or snail and enhance its chances for prervation. Water containing dissolved silica, calcium carbonate, or iron may circulate through the enclosing diment and be deposited in cavities such as marrow cavities and canals in bone once occupied by blood vesls and nerves. In such cas, the original composition of the bone or shell remains, but the fossil is made harder and more durable. This addition of a chemically precipitated substance into pore spaces is termed "permineralization."
Petrifaction may also involve a simultaneous exchange of the original substance of a dead plant or animal with mineral matter of a different composition. This process is termed " replacement" becau solutions have dissolved the original material and replaced it with an equal volume of the new substance. Replacement can be a marvelously preci process, so that details of shell ornamentation, tree rings in wood, and delicate structures in bone are accurately prerved.
反思1000字 Another type of fossilization, known as carbonization, occurs when soft tissues are prerved as t
hin films of carbon. Leaves and tissue of soft-bodied organisms such as jellyfish or worms may accumulate, become buried and compresd, and lo their volatile constituents. The carbon often remains behind as a
以上就是有关托福tpo阅读真题的部分内容，今天我们就先介绍到这里，稍后我么陆续为大家介绍更多有关 托福口语 、听力、写作的TPO全套内容，敬请期待。
相关字搜索： 托福tpo阅读真题
卧薪尝胆的意思
第二大经济体
