詞匯題：

negligible = minor, constraint = limit, commence = begin,

unexpectedly = surprisingly, enormous = huge, cluster = group

第一篇

TOPIC Distribution of Plants and Animals

講地球上植物之間的相似性要遠大于動物。以下闡明原因。原因一是植物很早以前就開始大范圍傳播，在大陸板塊分開之前就分布到各處，而動物出現得較晚；原因二是動物曾經歷了多次大滅絕，且之后出現的新物種代替了舊物種與原來很不相同，而植物則很長壽；原因三是動物群不如植物群一樣分散廣，每一個地方都有特定的動物種類，只有當大陸相連接的時候，動物才能進行傳播。植物群分散比較廣，并且即便是由于大陸漂移，植物也可以越過海洋進行種子的傳播。所以人們能看到各個地方相似的植物群出現。最后轉折，在亞洲和非洲兩地的動物相似性卻很高，是因為當時一度亞非板塊相連。

解析：

本文屬于生物學中的生物地理學biogeography范疇，從文章結構來看是典型的因果類文章，先說明結果，下面分別寫幾個原因，最后一段則是極具托福特色的轉折。其中，關于大滅絕的部分可以參照TPO閱讀文章Meteorite Impact and Dinosaur Extinction，關于植物傳播的部分可以參照TPO閱讀文章The Arrival of Plant Life in Hawaii。以下是與物種分布有關的內容擴展。

Species distribution

Species distribution is the manner in which a biological taxon is spatially arranged. Species distribution is not to be confused with dispersal, which is the movement of individuals away from their area of origin or from centers of high population density. A similar concept is the species range. A species range is often represented with a species range map. Biogeographers try to understand the factors determining a species' distribution. The pattern of distribution is not permanent for each species. Distribution patterns can change seasonally, in response to the availability of resources, and also depending on the scale at which they are viewed. Dispersion usually takes place at the time of reproduction. Populations within a species are translocated through many methods, including dispersal by people, wind, water and animals. Humans are one of the largest distributors due to the current trends in globalization and the expanse of the transportation industry. For example, large tankers often fill their ballasts with water at one port and empty them in another, causing a wider distribution of aquatic species.

There are three basic types of population distribution within an area. From top to bottom: uniform, random and clumped. Biogeography is the study of the distribution of biodiversity over space and time. It is very useful in understanding species distribution through factors such as speciation, extinction, continental drift, glaciation, variation of sea levels, river capture and available resources. This branch of study not only gives a description of the species distribution, but also a geographical explanation for the distribution of particular species. The traditional biogeographic regions were first modeled by Alfred Wallace in The Geographical Distribution of Animals (1876). These were based on the work of Sclater's terrestrial biogeographic regions. Wallace's system was based on both birds and vertebrates, including non-flying mammals, which better reflect the natural divisions of the Earth due to their limited dispersal abilities.

第二篇

TOPIC Determining the Age of Planets and Universe

宇宙里面組成的物質都是一樣的，形成的時間也比較相仿。科學家發現不同的的星球上留下的遺跡通過科學測量，月球和巖石形成的時間都是一樣的，得出結論，所有星球形成時間相仿。地球上有很多水，有腐蝕，不能作為參數進行比較。但是月球和小行星進行比較，目前人類史上沒出現小行星撞擊地球，但宇宙爆炸產生的小行星碎片已隕石的狀態掉落到地球上。

解析：

本文屬天文學內容，講解如何測量行星及宇宙的形成時間，文中談到各行星形成時間相同，這部分內容可以參照TPO閱讀文章Planets in our Solar System。以下為文中提到的幾個學術概念的解釋。

Big Bang Theory

Big Bang Theory, currently accepted explanation of the beginning of the universe. The big bang theory proposes that the universe was once extremely compact, dense, and hot. Some original event, a cosmic explosion called the big bang, occurred about 13.7 billion years ago, and the universe has since been expanding and cooling.

The theory is based on the mathematical equations, known as the field equations, of the general theory of relativity set forth in 1915 by Albert Einstein. In 1922 Russian physicist Alexander Friedmann provided a set of solutions to the field equations. These solutions have served as the framework for much of the current theoretical work on the big bang theory. American astronomer Edwin Hubble provided some of the greatest supporting evidence for the theory with his 1929 discovery that the light of distant galaxies was universally shifted toward the red end of the spectrum (see Redshift). Once "tired light" theories-that light slowly loses energy naturally, becoming more red over time-were dismissed, this shift proved that the galaxies were moving away from each other. Hubble found that galaxies farther away were moving away proportionally faster, showing that the universe is expanding uniformly. However, the universe's initial state was still unknown.

Expanding Universe Experiment

One way to understand the concept of an expanding universe is to draw dots, representing galaxies, on a balloon. As the balloon is inflated, each dot moves away from all the others. To a person viewing the universe from a galaxy, all other galaxies would seem to be receding. The distant galaxies appear to be moving away faster than the near ones, which demonstrates Hubble's law. Most astronomers now believe that this expansion will continue forever.

Redshift

Redshift, change, or shift, in the light radiated by an object, such as a star or galaxy, that indicates the object's motion. Scientists have used redshifts to measure the velocities (speed and direction) of distant galaxies. Knowing the velocities of galaxies helps astronomers understand how the universe is changing. This knowledge allows scientists to interpret the distant past of the universe and to predict the universe's distant future. See also Light.

Redshift only occurs when an object is moving. Another mechanism can also redden the light of astronomical objects, but it is not considered to be the same as redshift. Dust particles between stars are just the right size to scatter light with short wavelengths more than they scatter light with long wavelengths. As the light of a star passes through a cloud of dust on the light's way to Earth, more of the long, red wavelengths get through the dust than the short, blue wavelengths do. This makes the star appear redder than it really is, but the light that reaches Earth is the true red light of the star and has not actually shifted. See also Interstellar Matter.

Redshifts of galaxies allow astronomers to measure the distance from Earth to the galaxies. Knowing the distances to galaxies gives astronomers an idea of the way the universe is expanding and provides clues to the origin, evolution, and future of the universe. The relationship between the redshift (and therefore velocity) and distance of a galaxy is called Hubble's law, which was named after American astronomer Edwin Hubble.

第三篇

TOPIC Agriculture and Settlement around the Nile

有圖有真相：尼羅河流域地圖

主要講撒哈拉沙漠和尼羅河對居民的影響。大家都認為尼羅河對于居民的定居是積極意義的，沙漠有著消極的影響。但實際上兩個方面是相互影響。在很多年前，當時撒哈拉沙漠還是一片比較富裕的土地，土壤比較適宜，但是隨著氣候逐漸變干，撒哈拉沙漠已經不適宜人們居住，人們被迫遷移到尼羅河周圍，尼羅河那里比較適宜人類的居住，但是大洪水在尼羅河的泛濫導致在溪流邊上的人民到達介于河流和沙漠的一片土地上躲避洪水，退卻后，人們恢復正常的生活。隨著氣候的變化，越來越多額游牧主義社群開始定居下來sedentary lifestyle，以莊稼的種植和農業的發展來不斷的提供穩定的食物來源，其中談到非洲農作物源于東亞。

解析：本文屬于非洲農業史內容，講解尼羅河地區農業的特點，文章的重點在于理解造成農業發展的原因，類似講解農業發展原因的文章可以參照TPO閱讀文章The Origins of Agriculture。同時文章給出關于尼羅河和沙漠的比較和對比。以下為對于尼羅河地區農業的特點的介紹。

Nile River

The Greek historian Herodotus wrote that "Egypt was the gift of the Nile". An unending source of sustenance, it provided a crucial role in the development of Egyptian civilization. Silt deposits from the Nile made the surrounding land fertile because the river overflowed its banks annually. The Ancient Egyptians cultivated and traded wheat, flax, papyrus and other crops around the Nile. Wheat was a crucial crop in the famine-plagued Middle East. This trading system secured Egypt's diplomatic relationships with other countries, and contributed to economic stability. Far-reaching trade has been carried on along the Nile since ancient times. The Ishango bone is probably an early tally stick. It has been suggested that this shows prime numbers and multiplication, but this is disputed. In the book How Mathematics Happened: The First 50,000 Years, Peter Rudman argues that the development of the concept of prime numbers could only have come about after the concept of division, which he dates to after 10,000 BC, with prime numbers probably not being understood until about 500 BC. He also writes that "no attempt has been made to explain why a tally of something should exhibit multiples of two, prime numbers between 10 and 20, and some numbers that are almost multiples of 10." It was discovered along the headwaters of the Nile (near Lake Edward, in northeastern Congo) and was carbon-dated to 20,000 BC.

Water buffalo were introduced from Asia, and Assyrians introduced camels in the 7th century BC. These animals were killed for meat, and were domesticated and used for ploughing-or in the camels' case, carriage. Water was vital to both people and livestock. The Nile was also a convenient and efficient means of transportation for people and goods. The Nile was an important part of ancient Egyptian spiritual life. Hapy was the god of the annual floods, and both he and the pharaoh were thought to control the flooding. The Nile was considered to be a causeway from life to death and the afterlife. The east was thought of as a place of birth and growth, and the west was considered the place of death, as the god Ra, the Sun, underwent birth, death, and resurrection each day as he crossed the sky.