5. Permeated=spread throughout
6. Precede=occur before
7. Resemble=be similar to
9. Cultivate=encourage the growth of
TPO4-1Deer Populations Of The Puget Sound
Marsupials are any members of the mammalian infraclass Marsupialia. All extant marsupials are endemic to Australasia and the Americas. A distinctive characteristic common to these species is that most of the young are carried in a pouch. Well-known marsupials include kangaroos, wallabies, koalas, possums, opossums, wombats, and Tasmanian devils. Others include the numbat, the bandicoot, the bettong, the bilby, the quoll, and the quokka.
Marsupials represent the clade originating from the last common ancestor of extant metatherians. Like other mammals in the Metatheria, they give birth to relatively undeveloped young that often reside with the mother in a pouch, for a certain amount of time. Close to 70% of the 334 extant species occur on the Australian continent (the mainland, Tasmania, New Guinea and nearby islands). The remaining 100 are found in the Americas — primarily in South America, but thirteen in Central America, and one in North America, north of Mexico.
Taxonomically, the two primary divisions of Marsupialia are: American and Australian marsupials. The order Microbiotheria (which has only one species, the monito del monte) is found in South America, but is believed to be more closely related to Australian marsupials. There are many small arboreal species in each group. The term "opossum" is used to refer to American species (though "possum" is a common diminutive), while similar Australian species are properly called "possums". Again, shrew opossums are more closely related to australidephians than to true opossums.
托福阅读真题第二篇 印刷术带来的发展 历史类
原文回顾：印刷术早发明于德国，然后再欧洲各个国家主要城市广泛运用。随着大众需求的上升，press开始广泛印刷书籍，并且开始使用各国的方言包括德语法语等语言)，而不是学术使用的Latin and Greek被上述语言，成了少部分使用的语言工具。这些语言的使用也让欧洲人形成了民族认同感，慢慢的，书籍开始与policy无关，而仅仅取决于人们自己的需求。而且印刷的问世带来了许多的书籍，以前的手稿只能人手一份，而且不能编辑，不利于文化交流。有了印刷之后，可以出版更多权威的书籍，列举亚里士多德的例子。另外press不仅仅是印刷的地方，而是各种功能的集合体。
Printing is a process for reproducing text and images using a master form or template. The earliest examples include Cylinder seals and other objects such as the Cyrus Cylinder and the Cylinders of Nabonidus. The earliest known form of woodblock printing came from China dating to before 220 A.D. Later developments in printing include the movable type, first developed by Bi Sheng in China. Johannes Gutenberg introduced mechanical movable type printing to Europe in the 15th century. His printing press played a key role in the development of the Renaissance, Reformation, the Age of Enlightenment, and the scientific revolution and laid the material basis for the modern knowledge-based economy and the spread of learning to the masses.
Modern large-scale printing is typically done using a printing press, while small-scale printing is done free-form with a digital printer. Though paper is the most common material, it is also frequently done on metals, plastics, cloth and composite materials. On paper it is often carried out as a large-scale industrial process and is an essential part of publishing and transaction printing.
托福阅读真题第三篇 一种会发电信号的鱼 生命类
Weak Electric Systems In Fish
1. Some blind elephantnose fish produce weak electric signals that are used for detecting objects in their surroundingsa phenomenon called active electrolocation. These fish have specialized electric organs that discharge either in pulses or in a wave-like fashion, depending on the species. Although discharges follow one another almost continuously throughout the life of the fish, their power level is much too low to be detected by human handlers but potent enough to create a stable electric field around the body of the fish. When an object enters into this electric field, it causes distortions in the current that are detected by electroreceptor organs distributed over the fish's skin.
2. A weak electric system may have several uses, including the exploration of novel environments. For example, blind elephantnose fish can easily find the only opening that allows them to cross through a newly installed partition within their aquarium, even though they cannot see it with their eyes. Their electric sense must be implicated because when these individuals become electrically silent (unable to use their electric system through denervation of their electric organs), they can no longer find the opening.
3. During the 1970s, biologists became interested in the role of the weak electric system not only as a means of electrolocation but also as a means of electrical communication between individual fish. Communication is possible because the rate and waveform of the electric discharges can vary between species, between sexes, between individuals, or even between situations in the same individual. Moreover, some fish can temporarily interrupt their normally continuous train of discharges, and these pauses can be full of meaning. The effective range of communication by electric signals can reach a little over 1 meter depending on water resistance.
Electromagnetic field receptors (ampulla of Lorenzini) and motion detecting canals in the head of a shark
Active electrolocation. Conductive objects concentrate the field and resistive objects spread the field.
Electroreception, or electroception, is the ability to detect electric fields or currents. Some fish, such as catfish and sharks, have organs that detect weak electric potentials on the order of millivolts. Other fish, like the South American electric fishes Gymnotiformes, can produce weak electric currents, which they use in navigation and social communication. In sharks, the ampulla of Lorenzini are electroreceptor organs. They number in the hundreds to thousands. Sharks use the ampullae of Lorenzini to detect the electromagnetic fields that all living things produce.This helps sharks (particularly the hammerhead shark) find prey. The shark has the greatest electrical sensitivity of any animal. Sharks find prey hidden in sand by detecting the electric fields they produce. Ocean currents moving in the magnetic field of the Earth also generate electric fields that sharks can use for orientation and possibly navigation.
Electric field proximity sensing is used by the electric catfish to navigate through muddy waters. These fish make use of spectral changes and amplitude modulation to determine factors such shape, size, distance, velocity, and conductivity. The abilities of the electric fish to communicate and identify sex, age, and hierarchy within the species are also made possible through electric fields. EF gradients as low as 5nV/cm can be found in some saltwater weakly electric fish
The paddlefish (Polyodon spathula) hunts plankton using thousands of tiny passive electroreceptors located on its extended snout, or rostrum. The paddlefish is able to detect electric fields that oscillate at 0.5–20 Hz, and large groups of plankton generate this type of signal. See: Electroreceptors in paddlefish
Electric fishes use an active sensory system to probe the environment and create active electrodynamics imaging
In 1973, it was shown that Atlantic salmon have conditioned cardiac responses to electric fields with strengths similar to those found in oceans. "This sensitivity might allow a migrating fish to align itself upstream or downstream in an ocean current in the absence of fixed references."
Magnetoception, or magneto reception, is the ability to detect the direction one is facing based on the Earth's magnetic field. In 1988, researchers found iron, in the form of single domain magnetite, resides in the skulls of sockeye salmon. The quantities present are sufficient for magnetoception